Understanding prenatal testing

Learn about the different prenatal tests and their significance to you and your baby.

Prenatal testings

What are the different tests you can have done before your baby is born? Read on to find out.

Pregnancy is a time of great anticipation, and you’ll probably find yourself asking questions like these: Will it be a girl or a boy? Will the baby have your smile or his eyes? Will it have curly or straight hair?

But more than those relatively ‘shallow’ questions, more important ones about your baby’s health surface and can potentially overwhelm you: Will he or she be born with any abnormalities or birth defects? Will you experience any complications during birth? Will my baby be 100% healthy?

Now, while most babies are born healthy, concerns such as the ones mentioned are natural. Fortunately, you can take comfort in the fact that there are a number of tests available that can help identify potential health problems for you and your unborn child, some of which are treatable.

Thus, it is important to educate yourself and anticipate what you need to do, should any problems be detected. Remember, early detection means more time for treatment and planning various courses of action.

The purpose of prenatal tests

Some prenatal tests are routine in pregnancies and are mostly screening tests. These include blood tests and ultrasounds that can only identify if your baby is likely to have certain conditions but cannot diagnose these with certainty.

Diagnostic tests, on the other hand, will either be suggested to you or you may opt to take them. They usually test for chromosomal disorders, which refer to an abnormality in the structure or number of chromosomes.

The chance of a child being born with these disorders increases if the expectant mother is older. For example, the American College of Obstetricians and Gynecologists found that 1 in 1,667 babies born to women in their early 20s have Down syndrome, but this number increases to 1 in 378 in women in their mid-30s and 1 in 106 for 40-year-old women.

Thus, doctors would usually recommend older women or women with a family history of genetic disorders to take these tests. However, an expectant younger mom or one without any history can opt to take them as a precautionary measure as well.

If you’re pregnant, here are some diagnostic prenatal tests to consider:

Amniocentesis

What is it?

Usually conducted to detect chromosomal abnormalities such as Down syndrome, inherited metabolic disorders and some fetal infections.

Who should take it?

The test should be taken if you are above 35 years of age, have had a child with a birth defect, have a family history of genetic disorders or had an abnormal screening test.

When should it be done?

It is often performed between the 15th and 20th week of pregnancy.

How is it done?

The doctor will remove some amniotic fluid through the abdominal wall in the uterus during an ultrasound scan with a very thin needle. These cells are grown in a special culture and analyzed.

During the procedure, you may experience slight pressure or pain, but usually nothing more. Test results are ready within 1 to 2 weeks.

What are the risks involved?

Injury to the baby is rare. Risk of miscarriage is 1 in every 200 procedures. There is also a low risk of uterine infection and leakage of amniotic fluid.

Chorionic Villus Sampling(CVS)

What is it?

Usually conducted to detect chromosomal abnormalities such as Down syndrome and inherited disorders. The advantage of this test over amniocentesis is that it can be performed earlier, allowing parents to make decisions and receive counseling.

Who should take it?

The test should be taken if you are above 35 years of age, have had a child with a birth defect, have a family history of genetic disorders or had an abnormal screening test.

When should it be done?

Often performed between 10th and 12th week of pregnancy.

How is it done?

A needle is used to extract tiny placental tissue from your placenta during an ultrasound scan. The tissue is tested for birth defects because the baby originates from the placenta and the specimen would thus have the same chromosomes present in the unborn baby.

Mild pain is felt during the procedure and local anesthesia is used. Test results are ready within 1 to 2 weeks.

What are the risks involved?

About 1% of CVS performed result in miscarriage. There are also risks of infection and birth defects developing if the test is done too early in pregnancy.

Fetal Blood Sampling (FBS)

What is it?

Usually conducted to detect chromosomal abnormalities such as Down syndrome, inherited disorders, infections which can affect the fetus and anemia or low platelet levels in the fetus. The major advantage of this test is that it can be carried out quickly, which is helpful when the fetus is in distress.

Who should take it?

The test should be taken after an abnormality is noted on a screening test such as an ultrasound, when other test results are not conclusive or when you have been exposed to an infectious disease that could affect your fetus.

When should it be done?

Often performed between the 18th and 23rd week of pregnancy.

How is it done?

A fine needle is guided from the abdomen and into the uterus to extract blood from the fetus during an ultrasound scan.

Mild pain may be felt during the procedure and local anesthesia is used. Test results are ready within 3 to 5 days.

What are the risks involved?

About 1% to 1.5% of FBS performed results in miscarriage.

Did you have any prenatal tests done when you were pregnant? Let us know by leaving a comment below!

References:

Maternal Serum Screening for Birth Defects