Every kick, flutter and ultrasound image carries a reassuring message: your baby is growing. Part of the reason for these prenatal visits is to monitor the baby’s growth. Prenatal care relies on targeted tests that track how your baby develops and how well the placenta supports that growth. A failure to conduct or properly interpret these tests can put both mother and baby at risk. As a result, it is important to have a basic idea of what these tests are, what they look for and what can be done if the results are concerning.
Common prenatal tests
Typical prenatal testing within the first trimester often includes an ultrasound and maternal blood tests. These allow the medical team to check the fetus for physical abnormalities and risk of genetic or chromosomal abnormalities. Depending on the results of these tests, additional genetic testing may be helpful. Additional ultrasounds are common in the second and third trimester to continue to monitor growth and development as well as to check the cervix and placenta.
Glucose testing is common between the 24th and 28th week of pregnancy. This test checks for gestational diabetes. Additional tests often include Group B streptococcus, fetal heart rate monitoring, amniocentesis and chorionic villus sampling.
Antepartum testing
Certain pregnancies are at higher risk of stillbirth and can benefit from additional testing, referred to as ante-partum testing. Examples can include cases with pregnancy-induced hypertension, previous instances of fetal death and decreased fetal movement. The types of tests that medical professionals may recommend will vary depending on the details but can include:
- Nonstress test (NST): Measures fetal heart rate patterns in response to fetal movement
- Biophysical profile (BPP): Combines ultrasound observations with an NST to evaluate breathing movements, gross movements, tone and amniotic fluid volume.
- Modified biophysical profile: Usually pairs an NST with an amniotic fluid assessment.
- Contraction stress test (CST): Evaluates fetal heart rate response to uterine contractions
These tests are often recommended at 32 to 34 weeks of gestation but can be used earlier in certain circumstances. Abnormal results warrant further evaluation.
When acted on promptly, ante-partum testing may identify conditions linked to serious outcomes including hypoxic-ischemic injury, stillbirth, complications from fetal growth restriction, cord compression associated with low amniotic fluid and morbidity related to severe preeclampsia or placental insufficiency. While no test guarantees prevention, failure to order, interpret or respond to abnormal results can increase the risk of preventable injury or death.
Ante-partum and prenatal testing are cornerstones of modern prenatal care. Understanding the common tests and following through with timely follow-up can make the difference between routine delivery planning and urgent intervention aimed at protecting both parent and baby.