Testing, testing 1, 2, 3 and then some. Learn about the new NIPT test and other procedures available when you’re expecting.
You’re sitting there, anxiously awaiting the result of your home pregnancy test to reveal whether or not you’re going to introduce a bouncing bundle of joy into your life.
Finally! It’s true! You’re pregnant! But, wait … the tests are far from over.
Now that you know you’re pregnant, there are many more tests to be done and some to consider doing. They can be a little overwhelming to hear your doctor rattle off at just one doctor’s visit. Here, we round up the common and the new for better understanding.
Amniocentesis is a prenatal test in which a small amount of amniotic fluid is removed from the sac surrounding the fetus — at 15 weeks estimated gestational age (EGA) with the use of a long, thin needle and ultrasound for testing to look for certain types of birth defects, such as Down syndrome, a chromosomal abnormality.
“This test does carry a risk of causing miscarriage if performed prior to 23 – 24 weeks EGA, but after that it can cause pre-term labor, premature rupture of membranes, infection or abruption, stillbirth or other complications,” says Jason W. Pollock, M.D., F.A.C.O.G., of Murfreesboro Medical Clinic. “However, the risks of these adverse outcomes are quite low when an amniocentesis is performed in this country by highly-trained obstetricians and perinatologists,” he adds.
Because this test presents a small risk for both the mother and her baby, the prenatal test is generally offered to women who have a significant risk for genetic diseases. It’s offered to everyone, and you can opt out of having the test performed if you’d like.
If your pregnancy has become a little complicated, and you have what is known as a rupture of membranes (ROM), an AmniSure test will be performed — a vaginal swab to diagnose why you have ROM.
“A sample of fluid from the birth canal is tested for a protein that should only be found if the membranes surrounding the pregnancy have ruptured (AKA the water has broken),” Pollock explains.
“This determination is important in the pregnant patient as diagnosis of ruptured fetal membranes is of crucial importance at any term in a pregnancy for prompt hospitalization and for timely and proper treatment,” says Vicki Conerly, administrative director of Women’s Services at TriStar Centennial Women’s Hospital.
Biophysical Profile (BPP)
The BPP combines an ultrasound with a NST to determine fetal health during the third trimester. During this test, the breathing, movement, muscle tone, heart rate and amniotic fluid are documented and scored. “The total score will help decide the overall health and well-being of your baby and help your doctor determine if your baby should be born sooner than planned,” says Conerly.
Contraction Stress Test (CST)
A CST checks to see if your unborn baby will stay healthy during the reduced oxygen levels that normally occur during contractions when you’re in labor. This test includes external fetal monitoring and is done when you are 34 or more weeks pregnant. “For a contraction stress test, the hormone oxytocin is given to you in a vein (IV) to cause labor contractions,” says Conerly. “If your baby’s heart rate slows down (decelerates) in a certain pattern after a contraction instead of speeding up (accelerating), your baby may have problems with the stress of normal labor. A contraction stress test is usually done if you have an abnormal non-stress test or biophysical profile,” she adds.
Fetal Fibronectin (FFN)
The FFN is a test to predict your chances of pre-term labor. Fetal fibronectin is a protein that acts like a kind of glue — which helps the amniotic sac attach to the lining of your uterus. Your body makes FFN early in the pregnancy (up to 22 weeks) and again at the end of the pregnancy (about one to three weeks before labor starts). “This test is useful when a patient between 24 – 34 weeks EGA has symptoms that are concerning for pre-term labor,” says Pollock. “Its presence suggests an increased risk of pre-term delivery, whereas a negative result means the patient is very unlikely to labor in the next one to two weeks,” he adds. Detection of this protein may help your provider predict your chances of having premature birth, which is a birth that happens before 37 weeks of pregnancy.
Group Beta Strep
You’ll hear it commonly referred to as a strep test, but this test is not performed in the mouth. “Group B streptococcus (GBS) is a type of bacterial infection that can be found in approximately 25 percent of a healthy pregnant woman’s vagina or rectum,” says Conerly. If you test positive for it, it’s said that it can be passed to your baby during delivery. GBS affects about one in every 2,000 babies in the United States, however, not every baby born to a mother who tests positive for it becomes ill. GBS is rare, but the outcome can be severe, and that’s why it’s now a routine part of prenatal care.
Non-invasive Perinatal Testing (NIPT)
NIPT, or cell-free DNA, is a new test to screen for Down’s syndrome, trisomy 13 and trisomy 18. “There are small fragments of the baby’s DNA circulating through the mother’s bloodstream of sufficient quantity for collection after 10 weeks of gestation,” says Pollock. “By simply drawing a sample of the mother’s blood (which doesn’t pose a risk the pregnancy at all), the baby’s DNA can also be collected and studied. This is a major improvement in our ability to accurately detect these conditions while minimizing the false abnormal results that plagued the prior tests,” he adds.
Non Stress Test (NST)
You’ve probably seen a friend or two in the labor and delivery room with a couple of belts strapped across her abdomen. This is also done at different times during the pregnancy if your doctor sees a need for it. One belt measures the fetal heart rate and the other measures contractions. So, if you’re having some early contractions, this could be something your doctor can do in the office to check you out. Movement, heart rate and “reactivity” of heart rate to movement are then measured for 20 – 30 minutes.
Periumbilical blood sampling (PUBS)
PUBS is a diagnostic test that examines blood from the fetus to detect fetal abnormalities.
“This test is an extremely rare and technically demanding test whereby an amniocentesis is performed,” says Pollock, “but instead of sampling amniotic fluid, the goal is to stick the needle into the vein of the umbilical cord in order to sample the baby’s blood, in much the same way we have our blood sampled as adults.” The sample is sent to the laboratory for analysis, and results are usually available within 72 hours. “This diagnostic test is used to determine malformations of the fetus, fetal infection (rubella), fetal platelet count in the mother, fetal anemia and isoimmunization,” says Conerly.
“PUBS is only performed in dire circumstances and the risk of miscarriage is very high,” adds Pollock. “In unusual conditions, the needle is held into the umbilical vein and the baby can receive a blood transfusion while still within the womb.”
While it’s the most common and everyone has heard of them, do you really know what it’s for? During an ultrasound, images are captured allowing your doctor to examine the uterus. The very first ultrasound you’ll have will be to determine if you’re in fact pregnant. Then, the next ultrasound at about 20 weeks into your pregnancy helps check the growth of the fetus, the amount of amniotic fluid, maybe even the sex of the baby and more.
“An ultrasound scan is the most common of the prenatal tests and currently considered to be a safe, non-invasive, accurate and cost-effective investigation of the fetus,” says Conerly. “It has progressively become an indispensable obstetric tool and plays an important role in the care of every pregnant woman,” she adds.
“This is also a good time to verify the location of the placenta as this may impact the risk of labor and need for cesarean delivery,” says Pollock. “Measuring the cervix at this stage of pregnancy can help estimate the risk of pre-term delivery so that interventions to reduce this risk may be offered,” he adds.
That’s a good list of the most common prenatal tests and they are there to help moms-to-be during their pregnancies. Sometimes, it’s just a peace of mind knowing you’re baby is growing healthy and strong.
“I could go on for days on these topics and still barely touch the surface,” explains Pollock. “That’s why I believe wholeheartedly that early and consistent prenatal care is of paramount importance in maximizing the potential for the best possible outcome for mother, father and baby.”