Every pregnant woman needs certain routine tests during pregnancy. Some women may need additional tests depending on their age, family history, or ethnicity.
Some of these tests are screening tests and others are diagnostic tests. Screening tests are done to evaluate certain risks. These tests don’t diagnose any problem, but they are meant to assess the risk for any disease or condition. If any screening test result returns positive, your OB/GYN will explain what the test results mean and possible next steps.
Your OB/GYN may do the following types of tests during pregnancy:
Routine Tests
Urine Test: During each visit, your OB/GYN will perform a urine test to look for signs of diabetes, urinary tract infections, and preeclampsia.
Ultrasound Exam: Your OB/GYN will perform an ultrasound exam between the 18th and 20th weeks of pregnancy to check for any problems with the developing fetus. During an ultrasound exam, a gel is spread on your belly and a special tool is moved over it to create a “picture” of the fetus on a monitor.
Glucose Challenge Screening Test: This screening test is usually done between the 24th 28th week of pregnancy to assess your risk for gestational diabetes. You will be asked to consume a sugary drink and perform a blood test after 1 hour to measure your blood sugar levels. Your OB/GYN will do this test if you are at high risk for gestational diabetes. Women, who have a family history of diabetes, are obese, had a large baby in a previous pregnancy, or are having twins are considered to be at high risk.
Group B Streptococcus Infection Screening Test: This screening test is done between 35th and 37th week to find out if GBS bacteria are present. These bacteria can cause pneumonia and other serious infections to the infant. Women who test positive for GBS bacterial will need antibiotics when in labor.
Screening Tests
1-Hour Glucose Challenge Test: This is a screening test to assess the risk of gestational diabetes. This test involves measuring plasma or serum glucose concentration 1 hour after drinking 50 grams of a sugary drink. If the 1-hour glucose challenge screening is above a certain level, your OB/GYN will do a glucose tolerance test for further diagnosis.
Nuchal Translucency Screening Test: This screening test uses ultrasonography to measure the thickness of the back of the fetus’s neck between the 11th and 14th weeks. This information, combined with the mother’s age and the results of the serum screen, help health care providers determine the fetus’s potential risk for chromosomal abnormalities and other problems.
First Trimester Screening Test: Blood is drawn to test for PAPP-A and free beta-hCG (or hCG) and may be combined with performing a nuchal translucency ultrasound. This test helps assess the risk of Down syndrome as well as other chromosomal problems.
Maternal Serum Screening Test: This test is also called quad screen, triple test, triple screen, multiple marker screen, or AFP. This screening test is done between the 15th and 20th weeks of pregnancy. This test involves drawing blood and testing to measure the levels of certain substances that determine the risk of the fetus having chromosomal abnormalities and NTDs.
Chorionic villus sampling (CVS): Your OB/GYN may recommend this test if your fetus is at risk for a chromosomal defect or other genetic disorders. This is done between the 10th and 13th weeks of pregnancy. This test involves inserting a needle through the cervix or the abdomen to remove a small sample of cells from the placenta.
Amniocentesis: This test is done to detect chromosomal disorders, such as Down syndrome, and your infant’s risk for NTDs, such as spina bifida. This is usually done between the 15th and 20th weeks of pregnancy. After a local anesthetic is given, a thin needle is inserted into the abdomen to draw out a small amount of amniotic fluid and cells from the sac surrounding the fetus. The fluid is sent to a lab for testing.
Cell-Free Fetal DNA: This is a new, noninvasive test that uses the mother’s blood to look for increased amounts of material from chromosomes 21, 18, and 13. This test is done as early as 10 weeks on women whose age, family history, or standard screening results put them at higher risk for having a child with a chromosome disorder. Doctors don’t recommend this test for women who are at low risk or are carrying multiple fetuses.
Carrier Screening For Cystic Fibrosis (CF): This is a blood or saliva test that determines if the mother and father are carriers of the cystic fibrosis disease gene that affects breathing and digestion. A child inherits cystic fibrosis only if both parents are carriers of the CF gene.
As-Needed Additional Tests
Glucose Tolerance Test: Your OB/GYN may order this test if the 1-hour glucose challenge screening is above a certain level. You need to fast for at least 8 hours before the test. Your blood is drawn and tested for fasting blood glucose levels. You will be asked to consume a sugary drink, and your blood will be taken every hour for 3 hours to see how your body reacts to the sugar. Depending on the results, you may or may not be diagnosed with gestational diabetes.
Non-Stress Test: This test is also called a fetal heart rate monitoring test. This test is performed usually around the 28th week in the third trimester to monitor the fetus’s health. A belt placed around your belly measures the fetal heart rate while the fetus is at rest and while the fetus is moving or kicking. This test helps determine if the fetus is getting enough oxygen.
Biophysical Profile (BPP): BPP is a test that combines a nonstress test with an ultrasound to check the health of the fetus. This test helps monitor the fetus’s breathing, movement, muscle tone, and heart rate as well as the amount of amniotic fluid to determine fetal well-being. This test is done in the third trimester of pregnancy.
