Tests for Chromosomal Abnormality: The following are optional tests available to help detect chromosome abnormalities such as Down Syndrome. It is a personal decision whether to have these tests performed. Some reasons would be maternal age greater than 35 years old, a prior infant with abnormalities, or personal preference. If you are interested in these tests, we can have one or more scheduled:
CVS (Chorionic villus sampling)
This is an invasive test that can be done around 10-12 weeks. During a CVS, a small sample of cells is taken from the placenta.
Nuchal Translucency/ Ultra Screen
This is a minimally invasive test performed between 9-13 weeks from the last menstrual period. An ultrasound is used to measure the neck fold (or nuchal translucency) of the baby. A blood test is also performed that tests for Beta HCG and PAPP-A proteins. These combined tests can detect 90% of babies with Downs Syndrome and 97% of babies with Trisomy 18.
This is a maternal test offered from 16-20 weeks. Where blood is drawn to check the levels of 4 proteins (alpha-fetoprotein, HCG, estriol, inhibin A). This helps screen for Down’s syndrome, Spina Bifida and Trisomy 18. However there is a small risk of false positive (the test is abnormal but the baby is normal) and false negative results (the test is normal but the baby is abnormal).
The MaterniT21 PLUS test, developed and validated by Sequenom CMM, is a laboratory-developed test (LDT) that analyzes circulating cell-free DNA extracted from a maternal blood sample. The test detects an increased amount of chromosomal 21, 18, and 13 materials. The MaterniT21 PLUS test was clinically validated in a population of pregnant women with increased risk for chromosomal aneuploidy, including one or more of the following: Advanced maternal age, Personal/family history of chromosomal abnormalities, Fetal ultrasound abnormality suggestive of aneuploidy, Positive serum screening test
This is an invasive test that can be performed at 15-18 weeks. It will reveal the baby’s exact chromosomes. In this procedure, a sample of amniotic fluid is withdrawn from the mother’s abdomen using a needle. These cells are then cultured in the lab for about 2 weeks.
Group B Strep
At 35-37 weeks, a swab of the external vaginal area will be performed. This is a normal bacterium for adults and about 25% of adults will carry it at any given time. However it is not normal for babies. If you carry GBS you will receive an antibiotic during labor.
At 28 weeks in your pregnancy, and until you deliver, we are asking you to perform fetal kick counts. This exercise attempts to assure us that the baby is doing well in your uterus while you are away from our office. Fetal movement is a predictor of fetal well-being.
- At the time when the baby is most active, set aside one hour per day, once a day. Most often the baby will be most active in the early evening, but if the baby is most active in the morning, afternoon or in the middle of the night, use this time when the activity is the greatest.
- Sit on the couch, bed or sofa, and wait for the baby to move. Note the time on your watch or a clock with the first movement.
- Count 10 separate movements.
- After the 10th movement note the time
- If less than one hour has passed, the chances that the baby is doing fine is excellent. Resume your normal activities.
- If it takes longer than one hour for the baby to move 10 times, then call our office at this time.
The purpose of this exercise is to assess fetal well-being. If you do not feel the 10 movements we want you to call us so we can evaluate the baby and reassure you that the baby is fine, or recommend further evaluation including delivery if there is a problem.
You will be given a sweet drink and your blood will be drawn an hour later to screen for diabetes. If your first test is high you will be asked to do a second test that takes 3 hours. If your blood type is RH negative (eg. O-, B-, A-, AB-) you will receive a shot of Rhogam at about 28 weeks. It is very important that you obtain this medication so that your baby and all future babies can remain healthy.