by Jennifer Shakeel
Congratulations you are pregnant! The next nine months are going to be incredibly exciting for you. I am sure that you have heard the stories from other people you know about the weight gain, cravings and morning sickness. What no one ever tells you about are all tests the doctor is going to want to do on you while you are pregnant. When you first hear them talk about the tests the initial reaction is, “Why would I want to have that done?” Then they answer that question and your mind if overloaded with information and concern. The goal is not to worry or upset you. To help offset that anxiety I am going to go over the most common tests performed and tell you what to expect so that you are prepared when your doctor starts talking about them.
The best way to take a look at the various tests is to go through each trimester, so that you not only know what the tests are but you know when to expect them. In your first trimester the test will be a combination of blood tests and fetal ultrasounds. The purpose of most of the screening is to assess the risk of certain birth defects. The following tests are done during the first 12 weeks:
- Ultrasound test for fetal nuchal translucency (NT) – Nuchal translucency screening uses an ultrasound test to examine the area at the back of the fetal neck for increased fluid or thickening.
- two maternal serum (blood) tests – The blood tests measure two substances found in the blood of all pregnant women:
- Pregnancy-associated plasma protein screening (PAPP-A) – a protein produced by the placenta in early pregnancy. Abnormal levels are associated with an increased risk for chromosome abnormality.
- Human chorionic gonadotropin (hCG) – a hormone produced by the placenta in early pregnancy. Abnormal levels are associated with an increased risk for chromosome abnormality.
Depending on the results of those tests further testing may be done, including genetic counseling. I can tell you that even if the tests come back normal your doctor may send you for genetic screening for other reasons such as your age or ethnic makeup.
- During the second trimester there are more tests performed including more blood tests. These blood tests are called multiple marker and they are performed to see if there is a risk for any genetic conditions or birth defects. The blood test are typically done between the 15th and 20th week of pregnancy, with the most ideal time being the 16th -18th week. The multiple markers include:
- Alpha-fetoprotein screening (AFP) – a blood test that measures the level of alpha-fetoprotein in the mothers' blood during pregnancy. AFP is a protein normally produced by the fetal liver and is present in the fluid surrounding the fetus (amniotic fluid), and crosses the placenta into the mother's blood. The AFP blood test is also called MSAFP (maternal serum AFP).
- Abnormal levels of AFP may signal the following:
- open neural tube defects (ONTD) such as spina bifida
- Down syndrome
- other chromosomal abnormalities
- defects in the abdominal wall of the fetus
- twins – more than one fetus is making the protein
- a miscalculated due date, as the levels vary throughout pregnancy
- hCG – human chorionic gonadotropin hormone (a hormone produced by the placenta)
- estriol – a hormone produced by the placenta
- inhibin – a hormone produced by the placenta
Understand that the multiple marker screenings are not diagnostic tools, which means that they are not 100% accurate. The purpose of these tests is to determine if you are in need of additional testing during your pregnancy. When you combine the first trimester with the second trimester testing there is a greater possibility of the doctors being able to detect any abnormality with the baby.
There are other tests that are done during your second trimester if you want them done. One of which is the amniocentesis. This is a test where they sample a very small amount of amniotic fluid that surrounds the fetus. They do this by inserting a long thin needle through your abdomen into the amniotic sac. There is also the CVS test, which is the chorionic villus sampling. This test is also optional and it involves taking a sample of some of the placental tissue.
A test that all pregnant women have is the glucose tolerance test, which is performed during the 24 – 28 week of pregnancy. If there is an abnormal amount of glucose in the blood it could signal gestational diabetes. You will also undergo a Group B Strep culture. This is a bacteria found in the lower genital area and approximately 25% of all women carry this bacteria. While it causes no problem to the mother, it can be fatal to the baby. This means that if you test positive you will be put on antibiotics from the time labor starts until after baby is delivered.
I didn’t cover ultrasounds because everyone knows about ultrasounds and they are exciting and fun!
Jennifer Shakeel is a writer and former nurse with over 12 years medical experience. As a mother of two incredible children with one on the way, I am here to share with you what I have learned about parenting and the joys and changes that take place during pregnancy. Together we can laugh and cry and rejoice in the fact that we are moms!
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