For many moms-to-be, pregnancy is one of the most memorable and exciting times in their lives, but for others it can be a period of great confusion and fear. A significant part of that worry can stem from the fact that mamas don’t always understand what’s going on at their prenatal checkups. Study up on common procedures so you won’t be left clueless on appointment day. (Though if you do find yourself unclear about something, don’t hesitate to ask questions.)
“The purpose of prenatal testing is essentially to screen for Down syndrome and other common chromosome abnormalities called trisomies. These tests are offered to any expectant mother and they’re available worldwide,” says Sean Daneshmand, MD, physician at San Diego Perinatal Center and founder and CEO of Miracle Babies.
One of the first indicators that you’ve got a baby in tow will appear on a test strip in your bathroom, but urine tests will also be taken at your first prenatal appointment and the many that follow. According to the American Pregnancy Association (APA), these tests are used to assess bladder or kidney infections, diabetes, dehydration and preeclampsia by screening for high levels of sugars, proteins, ketones and bacteria that leak into your urine from your bloodstream. Urine tests pose no risk to the mother or baby.
If you didn’t test positive on the stick or received ambiguous results, you may have had to confirm your pregnancy through a blood test. These are conducted at your first appointment (and in some additional appointments) to test for blood type, Rh factor, glucose, iron and hemoglobin levels. The APA states, “A blood test is also used to assess whether you are immune to rubella, have a sexually transmitted disease, or if you have a toxoplasmosis infection, which is caused by eating infected, undercooked meat or contaminated fruits and veggies.” Aside from the annoying prick, blood tests pose no risk to the mother or baby.
One of the best and most comforting tests of pregnancy, the images you see on an ultrasound are created by high-frequency sound waves bouncing off of your baby’s form. There are many different kinds of ultrasounds (seven in fact!) that test for everything from a heartbeat to gestational age to malformation and fetal well-being. Your doctor will likely have a set schedule for ultrasounds, but if any complications arise, extra appointments may be added. Research shows no harm from ultrasounds when administered properly.
First trimester tests
“The most common test for the first trimester is the prenatal lab, which looks at maternal blood type and tests for rubella, hepatitis B and syphilis,” says Daneshmand.
First trimester screen
In addition to the prenatal labs, moms can also elect to take a noninvasive evaluation that uses a maternal blood screening in combination with an ultrasound evaluation. The first trimester screen (FTS) looks to identify the risk for specific chromosomal abnormalities like trisomy 18 and trisomy 21. Also, a nuchal translucency screen, which is conducted between 11 and 14 weeks, is used to screen for fetal abnormalities such as cardiac defects. “The test includes an ultrasound that looks behind the fetus’ neck and measures the distance between the skin and the soft tissue along with obtaining mom’s blood for PAPP-A and hCG,” says Daneshmand. Within about a week of ultrasound measurements being taken and your blood work being sent to a lab, your doctor will call to report the results. A positive screen doesn’t mean your baby actually has a disorder; it’s just a starting place for more in-depth testing and discussion. The FTS poses no risks to the mother or baby.
Chorionic villus sampling
If you or your partner possess certain risk factors for abnormalities, your doctor may suggest chorionic villus sampling (CVS). CVS is a diagnostic test that looks for chromosome abnormalities and inherited disorders. The procedure is usually performed between 10 and 13 weeks from your last menstrual period and involves removing some chorionic villi cells from the placenta (either transcervically or transabdominally) at the point where it attaches to the uterine wall. CVS does not test for neural tube defects and, according to the APA, carries a small risk of losing the pregnancy.
Second trimester tests
“During weeks 15 through 20 of the second trimester, the most common tests will be concerning chromosomal abnormalities and neural tube defects,” says Daneshmand.
Triple or quad screen test
The triple screen is generally offered to all moms but recommended for those with certain risk factors (such as radiation exposure and diabetes). It’s administered between weeks 15 and 20 of pregnancy and measures the levels of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and unconjugated estriol (uE3). Add on a test for inhibin-A and you have the quad screen. Both tests are used to check for Down syndrome, trisomy 18 and spina bifida. Results are weighed with other factors such as age, weight, ethnicity and gestation (as well as the results of prior screening tests) to calculate the possibility of genetic disorders. Both are non- invasive and pose no threat to the mother or baby.
If you get an abnormal result from the triple screen, your healthcare provider may recommend another diagnostic test called amniocentesis, which is typically performed between 15 and 20 weeks. The test can be used to check for chromosomal abnormal- ities and neural tube defects, as well as test paternity. Though it can identify certain disorders, it cannot decipher the severity of them. Amniocentesis is invasive, Daneshmand says, so the procedure does carry a small risk of losing the pregnancy. Many moms will elect not to have the procedure if they’ve already made up their minds about carrying a pregnancy to term or caring for a child with special needs.
Third trimester tests
“The most common tests during the third trimester [screen] for gestational diabetes,” says Liyun Li, MD, with Pacific Fertility Center in San Francisco. Though blood pressure, body weight, urine analysis, baby’s heartbeat measurement and growth of the uterus will be measured just as at previous appointments, she adds.
Glucose challenge screening and glucose tolerance test
Near the beginning of your third trimester, you’ll be given a sugar-laden beverage and instructed to consume it in a specified amount of time. When you’ve finished your drink, your blood will be drawn to test glucose levels in your body and determine how effectively you are processing sugar. If everything looks good, you’re in the clear. If not, you’ll need to come back for a glucose tolerance test. For this, you’ll be instructed to consume a limited number of carbohydrates in the three days leading up to the test and advised not to eat or drink anything during the 14 hours prior to your appointment. When you arrive, your blood will be taken to determine your blood glucose levels following the fast. Then after consuming another sweet drink, your blood glucose levels will be tested every hour for three hours. Abnormal test results indicate gestational diabetes and require a conversation with your care provider about the best way to manage it.
Fetal fibronectin test
Women showing early symptoms of labor may choose to take the fetal fibronectin (fFN) test between weeks 24 and 34. It’s conducted much like a Pap smear, and secretions are tested for the presence of protein fFN—the “glue” that essentially keeps baby in the womb. If fFN is detected, mom may be at risk for preterm labor; if not, she can avoid unnecessary intervention knowing it’s less than 1 percent likely she’ll give birth in the next 14 days.
Fetal nonstress test
A fetal nonstress test uses two belts attached to a mom’s abdomen, one to measure fetal heart rate and another to measure contractions. The test is used to monitor baby’s heart rate and movement. If baby is asleep, the nurse may use a buzzer to make your tiny one stir. According to the APA, these tests may be performed if a baby is not moving as frequently as usual, if you’re overdue, if there is any reason to suspect the placenta is not functioning adequately or if you are otherwise high risk. The fetal nonstress test poses no risk to the mother or baby.
Group B strep test
“Late in the third trimester (at 36 weeks), women are screened for GBS culture, which is a swab of the vaginal and rectal areas for a common intestinal flora: Group B streptococcus,” says Daneshmand. Approximately 25 percent of women carry the Group B strep bacteria, which can be passed onto their babies during delivery, so the Centers for Disease Control and Prevention (CDC) recommends this test routinely. If you test positive for GBS or have premature rupture of membranes, you’ll be given antibiotics to treat the infection. “Performing the recommended prenatal testing at the appropriate time during pregnancy will ensure a healthier outcome,” says Li. And knowing what tests to expect during your nine months of gestation will leave you feeling empowered and ready to make the right choices for your family.