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Birth Defects: Screenings & Tests Given During Pregnancy

Once you see those two blue lines your life changes forever. You move from being a woman to a mother in a matter of moments. You may begin to eat healthier and do everything within your power to prepare a better future for your child to come. Whether that's going green or simply preparing the nursery and making it perfect for the day you bring your little one home.

Part of preparing for your baby is seeing a gynecologist or obstetrician regularly and learning everything about pregnancy and the baby that is due in nine short months. This will come with routine procedures. As your pregnancy progresses your physician will perform certain screenings and tests to look for birth defects, or the risk thereof.

Sometimes, a pregnant woman may be given more tests due to age, family history, or history of pregnancy complications. Possibly your work or home environment can have an affect on your pregnancy as well. If it does, that may mean additional testing. Depending on your health and that of the baby, the doctor may even recommend invasive testing if there is a potential problem.

Here is a summary of some of the more common screenings and tests during pregnancy to determine any possible birth defects.

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10 First Trimester Screening

During the end of this first quarter of your pregnancy, a three part screening is often given to assess whether your baby is at risk or has already developed any birth defects. You may not even be showing yet, but your doctor will be able to determine so much through ultrasounds and blood work.

Although this can be frightening to a new mom-to-be, early screening is important when determining risk levels for birth defects. An important point to remember is that you, as the patient, are in charge of what screenings and tests you want to participate in.

Discovering your baby is at risk for a birth defect can be devastating, but decisions will have to be made, such as whether you wish to proceed with further, perhaps more invasive, testing.

9 Fetal Nuchal Translucency

During an ultrasound exam given during your first trimester, your doctor will give a test called the Fetal Nuchal Translucency (NT). The goal of this screening is to determine if there is any buildup of fluid behind the baby's neck. The ultrasound technician will ask you to drink lots of water and to not use the restroom before the ultrasound, as a full bladder is helpful for more accurate results.

If fluid exists under the fetus's skin at the back of the neck, it could potentially indicate Down Syndrome, heart problems, or other chromosomal abnormalities. However, a positive result simply means that there is an elevated risk and further testing would be needed. There are babies who show excess fluid who are born without any type of birth defect, but that is not very common.

8 Blood Work that Screens the Placenta

Blood work is also done during the first trimester as a screening for birth defects. The PAPP-A (Pregnancy Associated Plasma Protein Screening) and hCG (Human Chorionic Gonadotropin) will screen for chromosomal abnormalities. The PAPP-A is a protein that the placenta produces, while the hCG is a hormone produced by the placenta.

If the results indicate abnormal levels in either both or one of these screenings, further testing will be needed, as well as genetic counseling to educate you on what this all could possibly mean for you and your baby. If problems are detected this is where choices become tough for  new parents.

7 Second Trimester Blood Tests

During your second trimester your doctor will perform lots of blood work in an effort to weigh the risks of your baby having a birth defect. Often referred to as the multiple markers screenings, these blood tests are a screening, meaning abnormal levels require continued testing, often in an more invasive manner.

A pregnant woman's placenta produces hormones. Part of the multiple markers screening is testing the levels of hCG, Estriol, and Inhibin. If the hormone levels in any of these three come back abnormal, your doctor will discuss further testing options. Most pregnant women will also receive an ultrasound, especially if the blood results are abnormal, to try to determine why the blood work came back as it did.

6 Alpha-Fetoprotein Screening (AFP)

The AFP is part of the multiple markers screening during the second trimester, typically between week 16 and 20. This blood test can signal quite a few abnormalities. But like the other blood tests, results would only indicate a higher risk, and again, further testing would be needed.

The AFP is a protein produced by the liver of the fetus. It is present in the amniotic fluid and crosses over to the placenta and to the mother's blood. Abnormal levels can mean quite different things. It could mean there is a defect in the fetus's abdominal wall, a risk of Down Syndrome or other chromosomal abnormalities, or the possibility of an open neural tube defect.

However, it can also mean there are two fetuses (twins) or simply that the due date has been miscalculated.

5 Amniocentesis

If blood work from the first and second trimester screenings place the fetus at a very high risk of having a birth defect, a pregnant woman can opt to have an amniocentesis performed, typically between week 15 and 20. When an amniocentesis is done, the results are extremely accurate at predicting whether a specific birth defect actually exists with the fetus, but it is usually unknown as to the severity of that defect.

An amniocentesis involves taking a small sample of amniotic fluid. Doing so requires the physician to insert a long needle into the abdomen to collect the valuable genetic information that is stored in the amniotic fluid. The fluid is then sent to the lab, which will test the genes for chromosomal abnormalities such as Down Syndrome, as well as neural tube defects.

Many pregnant women are afraid to have an amniocentesis because of the risks it can bring, including miscarriages, preterm labor, infection, and fetal complications. Although there is always a risk, they are extremely rare.

4 Chorionic Villus Sampling (CVS)

With a CVS, a sampling of tissue from the placenta is taken. There are two ways doctors can go about obtaining the tissue. One is very similar to the amniocentesis, in that a needle is inserted into the abdomen to draw the tissue from the placenta.

However, the most common method of doing an CVS is by guiding a catheter through the cervix and up to the placenta, where the tissue sample is suctioned from the placenta. Doctors use an ultrasound to properly perform this task.

CVS is similar in regards to testing for chromosomal abnormalities as an amniocentesis, but it cannot screen for neural tube defects (as the amniocentesis can). It is also an earlier option for pregnant women who have elevated risks for birth defects, as it can be performed as early as 10 weeks into pregnancy. In most cases, CVS can also collect larger samples and provide faster results than with an amniocentesis.

Although the risks are rare, miscarriage and infection are concerns for many pregnant women who are recommended to undergo this procedure. Following the CVS, a woman may experience spotting or cramping.

3 Cell Free Fetal DNA Testing

A relatively new test, Cell Free Fetal DNA Testing is a less invasive manner of determining whether a fetus may have a chromosomal abnormality. The way it is performed is simply by taking a blood sample from the pregnant woman after 10 weeks, and testing it to see if there is any fetal DNA that has leaked into her bloodstream.

However, as it is only a blood test, it really can only show if there is an increased risk of the baby having an abnormality such as Down Syndrome. An amniocentesis or CVS, although more invasive, are far more accurate at determining birth defects.

2 Genetic Screening and Counseling

Early in your pregnancy, perhaps even at your initial appointment, the doctor's staff will ask you a series of questions. These questions will involve your personal history and the family history on both the maternal and paternal side.

If you have had a baby with birth defects in the past, whether or not that baby went to full term, you may be at an increased risk of birth defects with your current pregnancy. If there is a family history of birth defects or chromosomal abnormalities, that potentially could raise the risk levels, as well.

Your physician may suggest additional screenings and/or recommend more invasive procedures like the amniocentesis. However, even with a family history of birth defects, you may or may not be more at risk, but doctors do need to know your complete history so they can handle your current pregnancy with care.

1 Regular Ultrasounds

Ultrasounds are a regular part of visiting the doctor while pregnant. While most of us enjoy seeing the little baby on the screen, ultrasounds play a huge role in screening for birth defects. The ultrasound technician is always on the lookout for anything out of the norm, even as she may be pointing out those adorable teeny, tiny feet.

Around week 20 your doctor will perform an ultrasound that is often referred to as the anatomy scan. While this can be an exciting day for you, as the gender is typically revealed at this session (so if you don't want to know speak up!), they will also be analyzing every piece of that sweet baby of yours, looking for anything that may raise a red flag and require additional testing.

Sources: Healthline, What to Expect, Women's Health

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