Prenatal Testing: Genetic Tests, Screening Tests and Routine Tests During Pregnancy

Even before you are trying to conceive, you’ll get to hear about the prenatal testing such as amniocentesis and CVS. For safety reasons, these common tests in pregnancy are best not skipped. Yet they are optional and a pregnant woman can avoid them if she wills.

Screening tests only give results in ratio form. For instance, you get a Downs Syndrome risk test and the results come as 1:500 risk or 1:1000 risk. The lower the second digit, the higher is the risk. But even then, there is no diagnosis. You can get screening tests for checking your baby’s health or your health.

Tests such as screening risk of infectious diseases are optional. Here we will discuss the different prenatal testing use, risks and time to be taken. Common tests have been considered here. There are many other tests available for different purposes.

Prenatal Testing: Genetic Tests, Screening Tests And Routine Tests During Pregnancy
Prenatal Testing: Genetic Tests, Screening Tests And Routine Tests During Pregnancy

1) Tests Just Before Conception

Unless you’re one of those who had an unplanned pregnancy, you probably know what is ovulation tracking. Some women can do it without any aid just by calculations. Others just have sex every alternate day to increase their chances of getting pregnant. Someone might attempt coitus every day too. And some smart ones buy an ovulation test kit.

Those undergoing fertility therapy or having long cycles or irregular menses also use OTKs to find their fertile period. It’s easy to use and the most effective way of finding ovulation. Having sex a day before ovulation is most likely to get you pregnant.

a. Fertility Test

A fertility test includes all tests done for assessing your current reproductive health. It includes general blood tests for detecting levels of progesterone and estrogen. A medical history discussion about past incidences of surgeries, miscarriages or STDs also comes under it.

b. Ovulation Test

OTKs can be digital kits or strip tests. Doctors also use blood sampling for detecting ovulation. In any situation, the basis of the test remains the same. Along with the ovulation test, other fertility tests may also be done before TTC period.

What is ovulation test?

An ovulation test is a kit that detects a surge of LH in your blood or urine. This hormone starts coming along urine just a few hours before ovulation. Near ovulation, conception is most probable.

An ovulation test can either detect LH surge or estrogen surge. The tests that detect LH surge tell you that ovulation is just about to occur. Within 24 hours after the positive test, you will ovulate.

How is it done?

A home OTK has a general method of testing. A urine sample is taken and the OTK strip is exposed to it. The reaction takes place and the result is visible. Based on key given you can decide whether you have a positive or negative OTK.

When is it done?

Unlike pregnancy tests, ovulation test is not an early morning test. The hormone takes time to build up in your urine after you wake up. Early morning urine doesn’t have enough LH and gives a false negative. A dark line is positive and all lighter lines are negative. You don’t get a blank OTK because some LH exists in the blood.

Why should I take this test?

Taking an ovulation test makes it easier to time sex. Having too much sex causes depletion of your partner’s sperms. Similarly, exhaustion of the body makes it lose the receptivity for conceiving.

You must not take an ovulation test for natural contraception using abstinence. Throughout the month there is a slight probability of conception. Ovulation kit cannot detect that but its there.


The only risk with ovulation is inappropriate interpretation. Getting a positive test for many days implies that your LH production is excess. Pregnancy tests are straightforward while OTKs require some background personal information.

2) Pregnancy Detection Test

There are a variety of ways to detect pregnancy. Rarely when those test strips ditch a woman she can head for a digital test or blood test or even an ultrasound scan. Yes! An ultrasound is used to detect cryptic pregnancy or when the hCG levels are low.

a. Home Pregnancy Test

A basic pregnancy test uses hCG in urine to detect pregnancy. The pregnancy hormone reaches sufficient levels by 4 weeks pregnant and comes in the urine.

What is the test?

A pregnancy test is a strip that has hCG antibodies. These develop a color when hCG hormone attaches to them. Exposing a test strip to urine can help detect the presence of hCG. Just for your information, you can use the strip with blood too. After all the test is only for finding out whether or not hCG is present.

Digital pregnancy tests display the result as a flashing message. Pregnancy test strip shows a colored line other than control.

How is it done?

A pregnancy test is best done with early morning urine. Midstream test kits are directly exposed in urine stream. For dip strip sample of urine is taken in a container and the strip is dipped in. Results are displayed as the kit is designed.

When is it done?

A pregnancy test is done early in the morning. The reason is just to concentrate hCG in urine. You can take the test at night by storing urine or not peeing the entire day.

After a week from ovulation, you can begin taking a pregnancy test. Early pregnancy tests are able to detect pregnancy a week before due period.

Why should I take this test?

You can take a pregnancy test to find out the reason for the missed period. Taking a pregnancy test can also be a way to detect hCG from cysts. These form when a woman has PCOS. After IVF treatment taking a test will give you a false positive. Yet it will be a measure of having hCG in blood for superovulation.


False-negative test results are one of the few limitations. You can keep getting a negative test even when you’re actually pregnant. Not getting a beta hCG test after positive HPT, has a chance of undiagnosed abnormal pregnancy. Molar, tubal, and chemical pregnancy do give positive HPT but are not normal.

b. Beta hCG test

A beta hCG test is a pregnancy blood test. You will have to get it done at a lab or hospital.

What is the test?

A blood sample is taken from a vein. This is sent for detecting beta hCG levels. You will get a report with exact quantification of hCG. A home pregnancy test only detects the presence and is qualitative. Beta hCG test is quantitative. If the value obtained is in the range of pregnancy levels then the test reports me mentions it.

How is it done?

A blood sample is taken from venepuncture and sent for a laboratory procedure. Later you get the report mentioning the results. A positive test means you’re pregnant and have hCG more than 25 mIU/mL.

When is it done?

A beta hCG test can be done at any point. You can get it after a week or two weeks. Day and night don’t matter nor does any dietary precaution need to be followed. As general protocol doctors first ask you to take a urine strip test at hospital before withdrawing a blood sample. They may take both of the tests simultaneously too.

Why should I take this test?

You must take the test to know whether the positive test you got in HPT kit was a healthy pregnancy. A doctor will be able to diagnose any abnormal symptoms. Ectopic pregnancy is hazardous for fertility. In the condition, the fallopian tubes can burst and make conception impossible.

One will also need to take the test for PCOS diagnosis. Other causes of elevated hCG include tumors, drug analogs, etc.


There is no risk associated with beta hCG test as you’re under the supervision of a medical professional. Except for a mild sting, you won’t feel anything. Texts saying that withdrawing a small blood sample can cause dizziness are misleading.

3) Genetic test or Carrier Screening

A carrier of a disease is a person who herself doesn’t show the symptoms of the disease but can pass it on. Although the disorder didn’t occur in that individual carrying the defective gene, chances are high for the offspring to get it. Especially if two carriers mate then the child will have the disorder with a minimum chance of 25%.

There are three types of genetic tests – theoretical, non-invasive and invasive. Genetics tests tell about the probability of your future baby having a particular inheritance disorder. Parents get extremely nervous and worried when it comes to genetic tests.

Know that whatever be the results the choice and decision is still with you.

And there have been many cases defying the accuracy of these tests. Some have got a high-risk test and not had the disorder while others with no risk had it. Taking the test does two things – informs you and gives time to make decisions and prepare.

If no matter whatever the results are you will still have the baby then you could skip the invasive test.

What is this test?

A genetic test can be an analysis of your medical history. Blood tests followed by biochemical procedures can detect the presence of a particular genetic sequence. Scientists have identified the sequences (DNA content) that signs a disorder.

Paternity tests also have the same genetic basis. Both parents and children have common repetitive genetic sequences. Detecting the presence of the same sequence in two samples establishes a relation.

How is it done?

Non-invasive tests are just discussion between patient and doctor or taking a blood sample. For invasive tests, the doctor inserts an instrument that can collect blood or fetal tissue. The sample is then sent for further analysis.

When is it done?

Medical history tests or pedigree analysis are common practice since past times. In fact, earlier people did such compatibility tests before marriage. Pedigree is a history pictorial chart that highlights the affected and carrier of a particular disease through generations.

Even the Royals have a pedigree chart. Showing the inheritance of hemophilia, a blood clotting disorder,  of which The Queen was a carrier.

Non-invasive blood tests are done by the end of the first trimester. When the fetal mass starts shedding cells, a test can be done using the mother’s blood sample.

Invasive prenatal DNA tests are done later in pregnancy. They are optional like the other two. As they require intervention into the amniotic sac they’re risky.

These tests are for women with a family history of chronic or degenerative diseases. Women ahead of ideal maternal age also must take the test.

Why should I take this test?

You can take the test just for beforehand hint. There is absolutely no guarantee either way. Taking a test can help doctors educate you about possible treatment or complications.

Extra caution can prevent pregnancy complications. Current medical science progress is not enough for curing such disease in the womb.


  • Puncturing of the amniotic sac
  • Infection of fetus
  • Mother can go into depression and anxiety
  • Unnecessary stress due to the possibility of any disease
  • Second thoughts regarding the termination of pregnancy

4) Biophysical profile

The test is a combination of fetal stress and heartbeat test. During the test, the Fetal Non-Stress Test is done along with an ultrasound scan. During the scan, fetal movements are observed in response to a prod. Using a Doppler heart rate is under constant moderation.

What is the test?

A Biophysical profile test is an assessment of your fetus’s health. The non-invasive test measures the baby’s heart beats, checks movements and scans a picture.

Amniotic fluid levels are also measured to ensure efficient exchange of material between baby and you. Four quarters of the uterus are considered and volume in each of them is added.

With a biophysical test score, you can know how your baby is doing inside without actually letting any instrument inside.

How is it done?

A belt is placed around your bump for a non-stress test. There are sensors in it. Your baby may not respond initially if she is asleep. A buzzer beep can wake up the baby for the rest of the test. Some women report that drinking cold water or juice also generates a stimulus.

Ultrasound device moving on your belly shows everything inside. Amniotic volume is measured. It takes nearly half an hour for the entire test procedure to complete.

The test looks for 5 factors:

  • Fetal movement
  • Fetal heart rate
  • Amniotic fluid
  • Non-Stress Test
  • Fetal muscle tone and strength

Every factor has 2 points to it. There is a standard way of interpretation of each factor. The heart rate is either reactive or non-reactive. Depending on the results each is given points. The final grand total is the Biophysical profile score.

A score above 8 is normal, within 6-8 is uncertain and below that is negative or abnormal.

When is it done?

The test is done in the third trimester beyond the 32-week pregnant stage. In high-risk pregnancy, the test can be in the second half of the second trimester.

Modified biophysical profile test is done in case you don’t deliver even after completing 40 weeks. Obesity, overage, miscarriage history, and twin pregnancy make the test necessary for mums.

Why should I take this test?

You must take the test to know about your baby’s development. Lack of oxygen supply to baby due to the insufficient amniotic fluid can lead to stillbirth.

Gynecologists are able to foresee the complications during labor based on results. The test tells about the preparedness of you and baby for undergoing labor stress.


There are no risks of a Biophysical profile. However, there is no improvement in the pregnancy outcome just by taking the test.

5) Group B test

Group B streptococcus is a bacteria residing in rectal and vaginal passages of women. Healthy women have a limited number of bacteria. When the number of Group B strep increases beyond the normal range, the woman has an infection.

The infection can spread to the bladder and pass to the baby during labor. Pregnant women in the week 37 and ahead about to go into labor are screened for Group B strep. There is a 0.05% chance in every pregnancy to contract a Group B strep infection and pass it on to the neonate.

What is the test?

The Group B strep screening is prenatal testing that checks for the presence of bacteria in the rectum and vagina. Positive test results indicate colonization by the bacteria. Group B strep and throat infection causing streptococcus are different.

Taking intravenous Penicillin reduces the chance 4000 times for the baby. Even c-section will not prevent the passing of the infection if the water broke before it. Reliable treatment involves the use of antibiotics.

In case the mother passes on the infection to the baby, there are many consequences. Meningitis is the inflammation of brain-protective membranes.

Newborn with Group B Strep infection is at a high risk of meningitis, pneumonia and BP problems. The infection can take days to show symptoms or be early onset.

There lies a possibility for not passing on the infection even without treatment. But taking an intravenous antibiotic is safe and is the right caution. Not only the baby, you too can develop bladder and uterus infections.

How is it done?

Group B Strep Test is done in a lab that cultures the bacteria. A swab sample is swiped from vagina and rectum separately. These are sent for testing. You can expect the reports after 2 or 3 days.

When is it done?

If you test positive during early pregnancy, then you have to take the treatment. There is no rescreening to check again. In cases where the early prenatal testing didn’t show a positive test a cautionary test is again done in 37 weeks. Rupture of membranes prior to due date also makes it necessary to take a Group B test.

Why should I take this test?

You must take the test as Group B strep is fatal. There is a risk of stillbirth if the mother has Group B strep. Other than that heart stabilizing complications can occur in the neonate.

The mother and baby both can get a bladder infection. Kidney problems and digestive system can get hampered.


You might have a slight irritation in the vagina while taking out the swab sample. There is a risk of being allergic to the IV antibiotic. Consult your doctor about the best-suited antibiotic for you.

6) Dating Scan

An ultrasound scan for determining how far you’ve come along pregnancy based on baby’s growth is a dating scan. Based on the results your OB tells you your due date. A dating scan is the first ultrasound of pregnancy.

What is the test?

A dating scan is an ultrasound done in the 7 weeks of pregnancy. By the 7 weeks, pregnant time pregnancy test shows a positive result in most cases. The baby has a heartbeat and organs have started to appear. Sex determination is not possible.

Certain ranges of size and maturity of different parts of the body are standard. Comparing your baby to the set parameters the doctor is able to estimate the due date of pregnancy. In many cases, no heartbeat is detected in the dating scan. The thickness of the endometrial lining and gestational sac, at least give information about having twins.

A dating scan is also able to distinguish between a chemical pregnancy and a normal pregnancy.

How is it done?

If you take the test earlier than 7 weeks pregnant stage then it is transvaginal. A device attached to the catheter is pushed in the vagina. It produces an image of the inside of uterus on a screen.

You will not need to drink excess water for a transvaginal scan. And that makes it more ideal for pregnant women. A transabdominal ultrasound requires the bladder in a fully expanded state.

Thus, you have to drink a lot of water till holding your pee seems impossible! Expanded bladder allows the things across to it to be clearly seen.

The nurse applies some lubricant on your belly. Using a transducer the OB glides it all over your lower abdomen, showing the picture of internal organs. It can take up to 15 minutes for a complete scan. The OB or sonographer will point out the embryo for you.

In the first few scans, you won’t be able to make out much. Just the heartbeat will seem familiar stuff.

When is it done?

Dating scan purpose is to estimate due date and find out how far you are in pregnancy. Prenatal testing has a dating scan as the second test. By the 7-8 week of pregnancy, you’d get a dating scan appointment.

Why should I take this test?

You must take the test to know whether the baby’s development initiation has been the right way. Pregnancy due date will help you prepare and plan better. Your doctor will not be able to tell you whether or not you will have a natural delivery.

Yet you can make a decision based on the due date if you want to have an elective c section. Other than that twins detection and any implantation abnormalities are also shown in the scan.


There are no risks from an ultrasound. The process is non-invasive. Mild irritation in the vagina or from the lubricant is possible.

7) First Trimester Screen

The FTS is an optional prenatal scan cum fetal genetic test. Being a non-invasive genetic test many OB include it in the routine prenatal checkup list. A nuchal translucency scan and blood test make up the first-trimester screen.

One can take the first-trimester screen test after 8 weeks. If you take the test late in the first trimester then it can be a sequential screen. Being optional you can skip it and get a quad screen. It involves the same tests and more additional parameters.

What is the test?

The first-trimester screen is aimed at detecting genetic abnormalities in the fetus. Until the 6-8 weeks, the head and body of the baby are like a tailed mammal. After crossing the week, the head starts moving up and body straightens. Fluid under the neck area gradually changes in volume.

Measuring the volume of fluid under the neck is nuchal translucency named on the procedure involved. If there is a wide nuchal translucency result then there is a risk of genetic defects.

Translucency doesn’t mean a separation. Just being able to see space under the skin fold below the neck, is translucency. The skin can cover the entire fetus. Neural tube defects are not correctly screened via neural tube defects. Along with AFP levels test the screening is complete for neural disorders.

For, the blood test a sample of blood is taken and sent to the lab for testing. High levels of hCG occur due to molar pregnancy. Twins also give an hCG surge in blood more than a single fetus. Low levels of hCG could be because of a chemical pregnancy, insufficient production or inaccurate dating of pregnancy.

How is it done?

No preparation is required for the first-trimester screen. A blood sample is taken from a superficially visible vein. PAPP A and hCG levels are measured.

During the ultrasound, you just have to lie down. The doctor will perform the scan and compare the space above and below the baby. If space is enlarged then the test result is negative. A negative test doesn’t mean your baby has Downs Syndrome or other disorder. Risk of the disorder is higher as per the test in that situation.

When is it done?

First Trimester Screening can be done after 8 weeks in the first trimester. Nuchal translucency is a separate test in the 11-14 week. But you can get a combined test after 10 weeks.

Why should I take this test?

You can take the test to know about the possibility of having a chromosomal defect. Even if you’d still want to have the baby, you will be able to make the preparation. If not anything, at least you will have a mental determination to be ready for it.

After delivery and bearing the anticipation for long, the risk of postpartum depression increases a lot upon sudden shock.


Week 11-13 see an emotionally fluctuating phase. Getting a negative result can take a toll on a mother’s health. She may be carrying a perfectly healthy baby but because of test results live in anxiety.

It’s quite possible that you won’t have had a single thought about chromosomal defects. After seeing the results you may not able to handle the news if you get a negative result.

Getting a negative FTS result calls for more tests such an amnio, cordocentesis or Chorionic Villus Sampling.

8) Triple Screen

The triple screen is a genetic test for aneuploidy. Humans have 46 chromosomes. They occur in pairs. An abnormal number of chromosomes are termed as aneuploidy condition. An increase in the number of chromosomes is polyploidy.

Trisomy is triplet instead of a pair of chromosomes. Downs syndrome is caused by an extra copy of chromosome 21. The triple screen can detect it.

However, other prenatal testing are more advanced and a triple screen is just an additional option. Triple screen is able to assess neural tube defects because it checks high AFP levels.

What is the test?

Triple Screen is a blood test which measures 3 pregnancy-related hormones. Placental hCG, fetal AFP, and estriol produced by mother and fetus are the three factors of the triple screen. High levels of hCG indicate being ahead in pregnancy than expected. Similarly, low levels of AFP point out inaccurate dating of pregnancy. But the low levels of AFP could also be because of trisomy of chromosomes. Downs Syndrome, Patau Syndrome, and Edward Syndrome are some of the chromosomal disorders.

As triple screen doesn’t require any extra step other than the blood test, one can request it any time. If you want a Quad screen then PAPP A is also quantified in the same blood sample. A Quad screen is a triple screen and FTS combined.

How is it done?

A blood sample is collected. You get the reports in a weeks time at most. Your doctor may call you for a consultation afterward. Discussing the results of the test is important in the case of mothers above 35 years, or with a history of miscarriage. Family with a history of birth defects makes it more likely for the OB to suggest the test.

When is it done?

The triple screen can be done from 15 weeks pregnant time. But the results are more reliable in the late second trimester. It is a second-trimester screening. As there are no preparations needed, one can go for the test at any time of the day.

Why should I take this test?

You must take the test if you want to know about the possible dangers to your baby. If you have a chronic disease then also the test is a safe step to take. Viral infection, depression or radiation therapy patients also are advised to take the test.

Being on any medication during gestation, even antibiotics can affect your pregnancy outcome. As there is no harm, one can take the test.

Feeling overwhelmed by the anxiety of the results makes few parents elect out of such tests. You can control the anxiety by knowing that these are just screening. With whatever result, they hold a huge possibility of otherwise.


There are no risks associated with the non-invasive test.

9) Blood Test – Rh compatibility test

Red blood cells have sugars attached to them. Your blood group is a result of these sugars and their interactions. The reason why the blood group repeat check is done is to test the Rh factor. Even when a sibling or person aware of blood group offers to donate, the check for the Rh factor is essential.

There are antibodies against the other blood groups inside every human. For a person with blood group B, he has antibody type A. Just like that there is another factor is blood which is the Rh factor. A person either has it and is Rh+ (positive) or lacks it and is Rh-(negative).

What is the test?

A mother with Rh-negative blood can have a fetus with Rh-positive blood. The first exposure during labor will lead to mother producing antibodies against the fetus. And upon the second conception, the mother’s cells will attack Rh-positive fetus and destroy RBCs. Destruction of red blood cells rapidly causes oxygen deprivation and can lead to fetal death.

Giving an Rh-negative mother with an Rh-positive baby, an immunoglobulin suppressive shot subsides the attack. However, at times mother has made antibodies while pregnant due to internal hemorrhage. Blood transfusion through the umbilical cord and close monitoring are last alternatives.

How is it done?

Rh screening is a part of tests after the first prenatal visit. Your doctor will see the results and decide if you need the shot. Blood test just like any other is followed by immunological reactions.

When is it done?

The test is done in the first few weeks of pregnancy.

Why should I take this test?

You must take the test to avoid erythroblastosis fetalis. The condition is characterized by the killing of the fetus by an attack from the mother’s cells.


There are no risks of the test.

11) Quad Screen

After the first trimester screen and the triple screen comes to the Quad screen. All three factors are the same as the triple screen. Here hCG, estriol, AFP and inhibin A levels are checked. The new addition inhibin A tells about the risks of preeclampsia and genetic disorders.

The quad screen is modified multiple marker test. That is also the reason why the triple screen is now outdated. With the same procedure, an additional inhibin A increases the accuracy.

What is the test?

The test is a blood test to assess overall pregnancy health. Different hormones and factors being measured have crucial roles. Fall or rise in levels above normal causes abnormal results. These results mean that there lies a possibility of the child being born with the disease.

How is it done?

A blood test is performed. The reports show levels found in your blood. Next to it, a range of normal values is given. You or your gynae will compare the two. A little bit of high or low levels is not problematical. However, only a medical expert can decide how much beyond the limit is still not a disorder.

Standard ranges for each test are approved by the medical council or supervisory body of the region. Depending on both biological and abiotic factors the range is declared.

When is it done?

The Quad Screen is done during the second trimester. If a woman has pregnancy complications the OB may ask her to take the test earlier. Measuring the levels of inhibin A in the first trimester is rarely correct. Taking the test way early increases the chance of false-negative results. You or your fetus can be healthy and an early test will give negative results. That is because the normal values are for a stage of pregnancy. Naturally stages before it will have lower levels of hCG.

Why should I take this test?

Taking a Quad screen completes the non-invasive screening. If financial liability doesn’t exist then the difference is nothing. All three blood screening prenatal testing only withdraw blood. The volume of blood may be taken slightly more if multiple tests are to be performed. Quad screen leaves no room for doubts that a non-invasive test could clear.


Absolutely no risk exists while taking a Quad screening test in the second trimester.


Maternal Serum Alpha Protein is the fetal AFP entering the mother’s bloodstream. Just like previous screening tests, MSAFP looks for alpha-fetoprotein. Although the need for normal levels AFP is yet to be entirely described. Lack or excess of AFP signals developmental defects.

When the alimentary canal is not complete and closed, the AFP levels fall. Spina Bifida also reduces maternal levels of AFP. The factor rises slowly in the blood of the mother and may even stay low for a late trimester.

What is the test?

The MSAFP test is a blood screening. Often just as a part of the triple screen test, MSAFP is a parameter. Rather than a test, MSAFP is a measured protein during other tests. Later a detailed ultrasound helps establish a correlation between the results.

In the 18th week, every organ of the baby is working. The development is complete. And now only growth and continual of function remain. Thus the results will be most accurate then. But MSAFP can be taken any time from 12-18 weeks.

Some parents may feel like opting out of invasive tests. MSAFP acts like the reassurance of their decision. If the results of MSAFP are not normal then they can reconsider getting an invasive test. But if they’ve decided it for sure that no matter what they will continue with the pregnancy, they can skip this one too.

How is it done?

The MSAFP is a part of the triple screen test. It’s just like a routine blood test. Along with it, an ultrasound enhances the accuracy of the test.

When is it done?

MSAFP is a second-trimester screening done late. By the 17-18 weeks of pregnancy, the results are mostly accurate.

Why should I take this test?

One must take the test if you expect twin pregnancy. If you have a history or risk of a hereditary disease then get this test.


There are no risks except for anxiety before or after getting the results.

12) Chorionic Villus Sampling

An early invasive test, CVS, detects genetic make-up of your baby as early as 10 weeks. Before 10 weeks Chorionic Villus Sampling involves a risk of polydactyly. The condition is marked by a fused extra finger or toe.

Being pregnant in the late 30s or genetic disorder inheritance pattern requires an invasive test early in the first trimester.

What is the test?

During Chorionic Villus Sampling a small part of placenta tissue is removed. This is tested for genetic content. Being placental in origin the tissue matches with the fetus tissue. Thus, testing it gives a picture of the fetus genetics.

Placenta has tiny projections that keep beating in the fluid. They are responsible for conduction.

For removing it there are two paths – cervix or abdomen.

Chorionic Villus Sampling allows detection of diseases such as Downs syndrome and cystic fibrosis. But neural tube defects are not detected by it. An ultrasound done along the sample collection helps screen spina bifida chances.

Amniocentesis is more advanced and done later in pregnancy. If screening results are positive then amniocentesis is the way of detecting.

False-positive results can occur in the tests. Yet after getting a positive test the mental dilemmas are extremely draining. All these diseases have management therapies and counseling systems. But overall their treatment doesn’t exist.

How is it done?

For performing CVS prenatal test your doctor will ask you to fill up your bladder. Though your doctor will tell you the volume of water to drink, you must be able to judge your bladder state. If you already feel like going to the ease yourself then don’t drink too much of water.

After applying some antiseptics and gel your ultrasound sonographer will perform a scan. The scan will be transabdominal.

You can get cervical or abdominal CVS. For abdominal CVS a fine needle will be inserted into your bump. A sample will be removed using it. A thin catheter will be put through the vagina for transcervical CVS.

In both conditions, care will be taken to not even go near the baby. It can take up to 3 weeks for the results of CVS to come.

When is it done?

Chorionic Villus Sampling is done after 10 weeks. But the test is for the first trimester. If you have a tilted uterus that doesn’t allow transabdominal puncture then cervical CVS is done early.

Why should I take this test?

After getting a positive screening test CVS will actually detect the disease. Unless you are of those who would have the baby no matter what, then taking the test will only help you. Thinking and worrying about anxieties will not change the challenges of having a baby with the disorders.


Miscarriage risk exists after CVS. The Rh factor is fetal blood can cause the mother to produce antibodies. These can kill the fetus through a condition called erythroblastosis fetalis.

13) Amniocentesis

Regular amniocentesis is an invasive genetic test. A gynecologist will directly poke a needle through your stomach to baby’s amniotic sac. It may sound like a tyrant but the needle is extremely fine. As pregnancy progresses the fetal shed cells reach mother’s blood. Cell-free DNA is naked. Without a cell covering it proves to be ideal for quickly testing genetic information.

What is the test?

Amniocentesis is testing the baby’s health using amnio fluid. The fluid has cells, DNA and other hormones and factors. Measuring the levels and genetic tests on the amnio fluid reveal a lot about your baby. But the test punctures the amniotic sac. As a result, complications such as injury or amnio fluid can start leaking.

Amnio is also used for accurate sex detection. For checking the functioning of lungs another type of amnio called fetal lung maturity amnio. India has banned gender determination before birth.

The list of diseases that amnio can assess is longer than any screening tests. Tay Sachs, Downs Syndrome, Prader Will syndrome, and Marfan syndrome. A single mutation causes such genetic diseases. These diseases are diagnosed in the fetus by taking the amnio. Blood disorders such as sickle cell anemia and Thalassemia are also detected. Neurodegenerative disorders and cystic fibrosis check-in fetus is also a part of the amnio.

How is it done?

Taking amnio before 20 weeks requires drinking a lot of water to have a stretched bladder. Later, the reverse happens and a full bladder can come way and get a puncture during amnio.

For performing an amnio test the woman has to lie on an examination table.

The doctor will first clean the abdomen, bump region using an antiseptic. Followed by this he will collect a sample of amniotic fluid.

For doing that, he will insert a very thin needle into your abdominal area. Continuous monitoring using an ultrasound wand will guide him to prevent the needle from hurting the fetus.

The selection of the inserting point will be such that it cannot harm the fetus. And the depth to which the needle goes will be just slightly in the amniotic sac.

As the needle will touch and pierce uterus lining you might feel some cramps. No anesthetic is used during amnio. Sample volume taken is nearly 30 mL.

Your baby by the time of amnio is producing more than 2 spoons of amniotic fluid every week. So it will be replenished within a short time.

Your OB will send the sample for testing and you will get the reports from the OB.

When is it done?

Amniocentesis is done at different times during pregnancy. Between 15-20 weeks the purpose is to detect genetic disorder and risks. Later in the third trimester, it’s for fetal activity check. In special cases, the amnio done before labor is for predicting the course of events.

Why should I take this test?

The test helps you detect diseases from the results of other non-invasive tests. After getting to know of the risks it is one of few ways to diagnose the disorder before the baby comes.


Rh sensitization can cause the production of antibodies against a fetus in Rh-negative mother. Cramps and irritation are also common after an amnio. Miscarriage as a result of the cramps is possible. Other risks such as infection, injury, and fluid leak also exist.

14) Prenatal Cell-free DNA test or NIPT

Fetal cells shed and circulate in the mother’s blood. Placenta keeps forming new blood vessels. These cells release the genetic material free-floating into the mother. So, the mother has both her own and fetal genetic material in the blood.

Later in pregnancy the ratio of fetal genetic material increases. Thus taking a sample of blood from the mother gives enough cffDNA cell-free fetal DNA. By testing it, a diagnosis of genetic diseases without invasive methods is possible.

With the introduction of NIPT risk of amnio and CVS is avoidable. But if the results of the test are positive amniocentesis may be needed.

What is the test?

Non-invasive prenatal testing using cell-free DNA is a novel method. The diseases that can be screened include Downs Syndrome, Edwards Syndrome, and sex chromosomes related disorders. Fragile X syndrome is a disease of the sex chromosome.

NIPT performed along an ultrasound is a complete screening. Nuchal translucency scan along NIPT helps in screening other defects. A wider nuchal translucency indicates risk of spina bifida.

How is it done?

For performing NIPT small blood sample is needed. Using the molecular biology methods DNA is isolated from the blood. And then there are many ways to analyze the DNA obtained from the blood.

Entire genetic count and analysis of each fragment take time. But the results obtained are able to eliminate the chances of false-negative or positive tests.

In case, the mother has a genetic disease and her DNA gets analyzed accidentally the test will be false positive. It is difficult to distinguish whether the genetic content obtained has a mother’s or baby’s DNA. It’s best to take the test after 10 weeks to get accurate results.

When is it done?

The fetal fraction of cell-free DNA increases in mother’s blood after week 10. Once there is enough of fetal DNA the test is possible. If you take the test earlier than 10 weeks then you can get false results. Chances of analysis of the mother’s DNA increase. That is because the fetal fraction is less than 4%.

Why should I take this test?

Non-invasive tests save you from invasive procedures. Your OB will persuade you for one screening test at least. Yet it’s totally your choice whether or not you find the test useful for you.


There are no risks associated with NIPT.

15) Screening For Infectious Diseases

Pregnant women can pass on many infections to their fetus. The transfer is either placental or during delivery. For syndromes such as HIV, the screening is mandatory. However, for Cytomegalovirus Infection and other such infections, the screening is optional.

Only when you will see the symptoms of the infection, the screening will take place. Vaginal examination for BV and thrush is also optional. Screening for Hepatitis B and syphilis is also advisable by the end of the pregnancy term.

TB and Hepatitis C screening is also done in early pregnancy.

What is the test?

There are special screening tests for each infection. Pregnant women need to provide samples of urine or blood. Within a week she will get her reports. If she is positive for a particular infection then precautionary steps will be taken.

The urine culture test is for testing bacterial vaginosis. Another highly contagious infection is rubella. Almost every developed country has rubella vaccination as a norm for children.

A pregnant mother who has not had rubella nor vaccinated against it can get the infection. In such a situation the only way to stay safe is by avoiding contact with infected people. Vaccination during pregnancy is safe for limited infections.

Hepatitis B test is compulsory but hepatitis C is elective. Those who are at risk must get the screening for hepatitis C too.

Recently Zika virus screening during pregnancy has gained a lot of momentum. The fatal infection can be passed on to the fetus. Depending on your area and if you are going to travel while pregnant the screening is done. Similarly, TB screening is for women with a history or risk factors of the respiratory infection.

How is it done?

Each screening has a different test. For TB your throat mucus sample (sputum) is taken. You just have to spit in a sample collection container. After chewing a rubber band or inedible stuff the generated mucus is sputum.

For HIV and hepatitis tests blood sample and other screening are done.

Vaginal infectious diseases are screened by PAP smear or physical examination.

When is it done?

The screening tests are done in early pregnancy. But some tests like TB and hepatitis B are third-trimester screening tests.

Depending on the need the optimal pregnancy screening tests are done at various times. Some rare cases where the infection risk is high may even be repeated.

Why should I take this test?

You must take the test to be able to take the treatment or precaution at the right time. Even for syndromes like HIV the right treatment at an early stage can prevent the transfer to the fetus.


There are no risks of taking screening tests. Diagnostic tests are time taking. A screening to decide which diagnosis is needful reduces the number of tests. At times you can get a false negative result and have the infection.

Every test has an accuracy rate. Nothing will interfere or affect your pregnancy health by taking a screening test.

16) Paternity Test or NIPP

NIPT and NIP are named similar because of the same procedure. NIP is a non-invasive paternity test. Knowing the biological father of a child is important for multiple reasons. The basis of all of them is to share the legal responsibilities.

The conventional paternity testing is done using fetal DNA. For that either you have to get an amniocentesis or Chorionic Villus Sampling. There are a lot of risks including miscarriage. The alternative to amnio and CVS is waiting until the birth of the baby.

An advanced method of checking the paternity of a child while you are pregnant is NIP.

The limitation of the test is not being able to establish the paternity of twins. That is because the DNA profile cannot be identified with one of the twins specifically.

What is the test?

The test is a blood test of mothers sample which has fetal DNA to match along with the possible father. After the 8 weeks of pregnancy, the fetal DNA starts floating in the mother’s bloodstream.

Using the test both DNA from fetus and father can be matched for checking similarities. The genetic code has repeated sequences that run in family.

If you suspect one of two people to be your child’s father then you will get results stating probability. For a man who is not likely, you will get a 0%. In case the expected father is the biological father then the probability will be 99% or higher. 100% of results cannot be obtained because some dissimilarity does exist in two individuals even if father and offspring.

How is it done?

A non-invasive paternity test is done my withdrawal of blood from mother. The blood has DNA from mother and fetus. Using scientific research methods the fetal DNA is isolated.

After that, the sample from probable father is taken. Two people can also give their samples together. Depending on your lab’s protocol you will have to decide and follow.

Then within a week’s time, the tests are done and reports prepared. With the probabilities of each man, you will get the results.

When is it done?

The test can be done after you are two months pregnant. Accuracy of the test is reliable after fetal DNA fraction in the mother’s bloodstream is 4%. Testing too early will pose a risk of analyzing the incorrect DNA or not being able to perform the test.

Why should I take this test?

You must test because of emotional and legal issues. Not knowing the real father can be an emotional burden. And instead of knowing the real father is there along with you, can be a boost to your pregnancy.

For legal reasons, identifying the biological father helps with custody, finance, etc.


There are risks of miscarriage and stillbirth with amnio and CVS paternity tests. NIP doesn’t pose any risks.

17) Gender Detection Scan

Gender detection scan and DNA karyotype are non-invasive ways for detection of gender. Scanning is a more common way for detection of gender after the 16-18th week. Before that either the genitals are not formed or the baby position isn’t suitable.

Even after the stage, there can be false results. Your baby can be playing with the umbilical cord giving a false impression.

What is the test?

Medical professionals use set patterns and theories for differentiating between a girl and a boy. Penis of a boy baby is the easiest and clearest sign for gender detection. If the penis is there or not is the first thing to look for.

With advancing technologies, now there are 4D ultrasounds. There you can see the baby as a whole. Testes or labia are clearly seen in a 3D or 4D scan.

How is it done?

There is nothing different in a gender detection scan. Just that the purpose of any scan is to assess the overall development of the baby. The second-trimester scan can involve gender detection if you opt for it.

Make sure that your country has legalized prenatal sex determination.

When is it done?

By 16-18 weeks pregnant stage, sex determination is accurate. Before that stage, a lot of anomalies prevent accurate gender detection.

Why should I take this test?

There is absolutely no need to take the test unless you want to. Maybe it will help you decide nursery decor or baby clothing beforehand.


There are no risks in gender detection scan expect for the legalization of the procedure.

18) Nuchal Translucency

Amongst the tests for genetic disease detection, nuchal translucency has a low false-positive rate. By measuring PAPP A and hCG along the test becomes even more accurate for detection of Downs syndrome. Latest developments include observing the nasal bone and respiratory tract efficiency.

What is the test?

A fluid collects near your baby’s head underneath. Once the head starts moving up and body straightens the volume of the fluid reduces. The ratio of the volume of fluid above and below the neck change with the stage of development. Unless there is something not right the fluid under neck reduces and narrows out.

Seeing the difference in volume near the baby and away, towards the sac, tells about the risk of Downs Syndrome. Neural tubes defects are not correctly predicted by the test.

A sonographer is able to view and analyze the features of the fetus. Using certain parameters the volume of fluid is measured. If the nuchal translucency is wide then results are negative.

Without any blood tests, the genetic disease screening test is possible with an NT scan.

How is it done?

For performing a nuchal translucency scan the sonographer will apply some gel on your belly. As the test is done is late first trimester you might need to drink extra water to stretch your bladder. Later you will lie down on an examination table.

All of your body will be covered and just the bump exposed. Using an ultrasound wand the sonographer will display the images on a screen. Either the reports will go to the OB or you will get them to carry along.

A negative test means that your baby has a wide nuchal translucency. That could be just due to incorrect dating of pregnancy too. In the next appointment, your OB will interpret the data.

When is it done?

The nuchal translucency scan is optional for first-trimester screening. If you received unsatisfactory results then the test may be repeated later again.

Why should I take this test?

You can take the test for the ease of screening method. Other than that knowing the risk of genetic disease can help you get appropriate counseling. Always remember that nothing will be done to you or your baby without informed consent.


There are no risks of nuchal translucency.

19) Fetal Non-Stress Test

Fetal Non Stress Test is a test measuring fetal heart rate during her own activities. It doesn’t lay any stress on the fetus for taking the test. At most your OB uses a buzzer or asks you to caress or walk to wake the baby for the test. A belt placed on your belly before the test has a heartbeat sensor.

What is the test?

Fetal NST measures a baby’s ability to move and tolerate stressful situations. Oxygen supply reaching the baby must be enough in order for her to be energetic. The results of NST are reactive or non-reactive. A positive test is the one where the baby is reactive and has an increased heart rate during movements. A baby who doesn’t receive enough oxygen will be non-reactive. That doesn’t necessarily mean a lazy baby and instead could be a warning for preeclampsia.

How is it done?

During a fetal non-stress test a nurse will place a belt on your bump and your OB will conduct an ultrasound. The belt will measure fetal heart rate while the ultrasound will show your baby moving.

When is it done?

Fetal Non Stress Test is done after you are 28 weeks pregnant. Upon a certain prescription or before proceeding for induction of labor the test can be done.

Why should I take this test?

The test is a method of finding out how prepared you and your baby are for undergoing labor.

You must take the test to allow the gynecologist to predict and guide you about labor.


No risks are associated with the fetal Non Stress test.

20) Glucose Tolerance Test

The glucose tolerance test is the most basic diabetes test. During pregnancy, gestational diabetes can occur. That is because your insulin can get overwhelmed with the extra calories and baby’s needs. Temporarily it can lead to diabetes. After the delivery of the baby, the condition subsides.

But having diabetes while pregnant affects labor and pregnancy outcome.

Blood pressure fluctuations due to inability to manage blood glucose are symptoms of gestational diabetes. Women with a family history of diabetes are at a higher risk. And then need to take the test earlier.

Your gynae will recommend you to get the test in the prenatal visit during the last weeks.

What is the test?

The glucose tolerance test or oral glucose test is an assessment of the body’s sugar utilizing abilities. Basically, the secretion, action, and function of insulin are being monitored.

A sugar load is put on the insulin and its activity is observed by withdrawing blood samples.

Glucose utilization has set ranges after a few hours from the meal. Just after a meal within the first hour, the sugar levels don’t peak up. They do go a little low before starting to rise. That is the time for insulin activation. And during that period glucagon is acting to increase blood glucose.

Once one and a half-hour pass the sugar levels increase. Later by the end of 2 hours insulin causes reestablished normal osmolarity of blood sugar.

How is it done?

For performing the test you will have to go fasting for more than 8 hours. You can go in the early morning without eating anything. The one-step test will require to drink a 75g glucose drink. The volume will be small to make it concentrated. Different glucose concentration is used for two-step GTT.

When you are done drinking, a blood sample is withdrawn just after that, called zero hour. Followed by it after an hour another sample is taken. Then after half-hour another sample. And so on samples of blood are taken until 2 hours are complete.

For the two-step test, you can go without any fasting. A higher concentration of glucose is used here. If the levels after an hour are in the range 130-145 mg/dL then the test finishes. If your levels are higher then you have to come for a fasting GTT.

These samples are tested for insulin activity. Plotting a graph it is seen if there is a belly shape with certain characteristics.

When is it done?

Glucose tolerance test is done during the 24-28 week pregnant stage. For women with a family history or high sugar levels in urine, the test can be earlier.

Why should I take this test?

Diabetes during pregnancy can cause a lot of complications. Fainting and dizziness are the less serious ones.


Drinking sweet syrup is not a pleasant experience. Take it slow else you might feel like puking. A rest day can be tiresome as you will feel giddy of the taste. You may have to answer a few extra nature’s calls.

No, big issues or risks crop up after a GTT.

21) Urine Tests

A part of the routine prenatal examination, urine tests can tell about various organs. Composition of urine changes in different conditions. Examples of it are when you start getting LH in urine and hCG in urine near ovulation and pregnancy.

Presence of proteins, sugars, ketone, and bacteria is urine indicate disorders like diabetes and STDs.

What is the test?

A urine analysis is checking urine contents. A normal adult urine has a set composition. Glucose doesn’t cross kidney filters. If it does then there has to be some metabolic disorder.

Similarly, Proteinuria in pregnancy is a sign of preeclampsia. Ketones in urine could be because of metabolic disorders. Presence of bacteria in urine sample other than normal vagina bacteria are indicators of infection.

Other than that, urine analysis also establishes your state of dehydration.

For symptoms like swelling, high BP, burning whole urinating and weight loss, a urine test is conducted. Even if you have a fever while pregnant your urine sample will definitely be taken.

How is it done?

You have to provide a clean sample of urine by collecting it in the provided container. Avoid drinking too much water before giving the sample. Diluting the sample will be of no good. Too much of the sample is just a waste. Your doctor may mention the volume the needed.

Storing urine overnight is safe provided you can keep it in the refrigerator. Indeed not possible for many people.

When is it done?

Whenever you will go for a routine prenatal checkup a urine test is done. At the first prenatal visit, a test is done for pregnancy confirmation.

Later if you report the symptoms such as swelling, weakness, or itching then a test will be done.

Why should I take this test?

You will have to take the test for pregnancy confirmation. Same goes for the first prenatal visit urine test. There is not much to do in it.


No risks are involved except contamination of the sample. Make sure you don’t touch the lid from inside or keep the container in a dirty place. Don’t douch before collecting the sample.

22) Kick counts

A kick count is a self-test to track your baby’s status. Not really a prenatal test but kick count charting will help you keep a daily track of the baby. Every baby has a certain sleep-wake and activity cycle. Counting the movement of the baby over a period of time tell about the growth. Once you’re past 35 weeks the movements reduce.

Squish and flutter don’t count as kicks. Rest movements such as rolling also come under kicking in early weeks. You will feel the movements in the 16-25 weeks.

Women who had a miscarriage, report having felt lesser movements a few days before it. A threatened miscarriage can be prevented by having knowledge of your baby’s kicks. You cannot suddenly or casually feel the difference.

Tracking the kicks at the same time every day will gradually make it familiar.

What is the test?

Kick counts tracking is a common practice more than a test. But it’s a way of finding your baby’s health status.

Baby’s movements are the only way to know if your baby is fine without having scans or tests. Using a kick monitor you don’t have to do anything. And even manually there isn’t any problem while kicks counting.

How is it done?

The kick counting method is simple. Using a kick monitor the test gets simpler. For doing it manually you will have to lie down and cut out everything.

Just caress your bump and note the time. If you don’t feel any movement then raise your legs up and drink a glass of fresh juice with ice.

Then take a journal and note the first kick and continue until 120 minutes pass by. Once you cross half time then add a slash.

When is it done?

You must start doing it in the late second trimester. Once you have felt a kick then you will soon know it. The time of the day your baby is active is most suitable. Waking up your baby at random times for the tracking is of no use. A sleepy baby won’t be as active.

It’s best to first identify your baby’s routine. Then time the test. Take the test every day at the same time.

Why should I take this test?

Your OB will definitely ask you to track your baby’s movements. Baby facing intrauterine growth restriction will first stop moving. Being totally aware of your baby’s routine will also help you to time your activities.


There are no risks. You may just become a little anxious about a slight change. Over time you will know when to worry and not.

23) Ultrasound

An ultrasound is a scan to look through your bump. The old but most common ones form images of the baby as shadows. Waves hit and bounce back or pass through forming images. More advanced sonograms are able to show clear pictures of cells and surrounding areas.

Doppler ultrasound or cardiography detect and show the fetal heart rate. Earlier during 7 weeks scan heartbeat could be absent. Now it rarely happens because of the advanced sensors.

What is the test?

An ultrasound is a procedure for displaying the inside of your uterus on a screen. Although transvaginal ultrasound requires insertion of the instrument inside the body, rest all don’t. Without actually going inside the baby and amniotic sac can be observed. Every stage of development is monitored by different pregnancy ultrasound.

There are many types and reasons for getting an ultrasound. Almost for every symptom, you report especially regarding the abdomen your OB will ask you to get a scan.

How is it done?

As described above, an ultrasound wand placed above your bump or taken inside vagina forms the picture inside. A layman will find it hard to interpret the standard ultrasound. The 3 D or 4 D ultrasound are easier to understand and more informative.

When is it done?

Ultrasound for the fetus is done after 7 weeks. They can be done multiple times as per your will. If only the recommendation based is considered then you will have a minimum of 7-8 scans.

Why should I take this test?

Ultrasound scans are important as they’re the only way to see what’s going on inside. A lot of conditions don’t manifest externally during early pregnancy. Scanning is safe and a precautionary routine for prenatal testing.


Ultrasound waves are safe and pose no risk.

24) Cordocentesis

Umbilical Blood Cord Sampling is the last alternative after an amnio, CVS and ultrasound don’t give conclusions. The test requires a blood sample directly from the fetus.

Upon infections like rubella or hemolysis cordocentesis becomes unavoidable. You can still say a no for it. But it’s only recommended when no other option is left.

What is the test?

Cordocentesis uses fetal blood for detection of Downs Syndrome and genetic disorders. Neural tube defects are not detected by it.

When the amniotic fluid or mother’s blood isn’t able to provide the required test sample then fetal blood is needed.

How is it done?

The OB uses a high accuracy ultrasound and inserts a needle inside the umbilical cord. Withdrawing a sample of blood from the site of attachment near placenta the needle is taken out. You get the results after 48-72 hours.

When is it done?

Cordocentesis is the final resort and is only recommended then. The test is safe after 17 weeks. Even then a certain risk of miscarriage due to excessive bleeding from puncture site exists.

Why should I take this test?

Only a medical practitioner can ask you to take the test. If other tests don’t give a clear answer then you might be willing for umbilical blood sampling.


There is a risk of miscarriage, infection, bleeding, and premature birth.

Prenatal Testing: Genetic Tests, Screening Tests And Routine Tests During Pregnancy
Prenatal Testing: Genetic Tests, Screening Tests And Routine Tests During Pregnancy