While you are pregnant, your doctor may do tests to check your baby’s health. The tests may be done at any time while you are pregnant. Tests may be needed for women who:
Have a high-risk pregnancy
Have a health condition, such as diabetes
Have had complications (problems) in a prior pregnancy
Have a pregnancy that lasts longer than 40 weeks (overdue)
The tests may be done more than once so the doctor can track the progress of the baby over time. They will help the doctor find problems or things that are not normal (abnormal). Talk to your doctor about your tests and the results.
Test results that are not normal aren’t always a reason to worry. A lot of healthy babies have results that are not normal. Your doctor can help you understand what your test results mean, and what kind of care is needed for your baby.
Non-Stress Test (NST)
A healthy baby’s heart rate will rise from time to time. During the NST test, your doctor will watch to see if the baby’s heart rate goes faster while resting or moving. You will receive no medicines.
If the baby’s heart rate does not go up on its own, you may be asked to rub your hand over your belly. This may wake up a “sleepy” baby. A device may also be used to send a noise into your belly. It will not cause any pain.
You will be hooked up to a fetal monitor, a heart monitor for your baby. If the baby’s heart rate goes up from time to time, the test results will most likely be normal. NST results that are "reactive” mean that the baby’s heart rate went up normally.
“Non-reactive” means that the baby’s heart rate did not go up enough. If the heart rate does not go up enough, you may need more tests.
Contraction Stress Test (CST)
If the NST results are not normal, you may need a contraction stress test (CST). This test will help the doctor know how well the baby will do during labor.
Labor is stressful for the baby. Every contraction means the baby gets less blood and oxygen for a short while. For most babies this is not a problem, but some babies have a hard time. A CST shows how the baby’s heart rate reacts to the stress of contractions.
A fetal monitor will be used. You will be given oxytocin (Pitocin), a hormone that makes the uterus contract. The contractions will be like the ones you will have during labor, only milder. If the baby's heart rate slows down rather than speeds up after a contraction, the baby may have problems during labor.
Most women feel mild discomfort, but not pain.
If the results are abnormal, your doctor may admit you to the hospital to deliver the baby early.
Biophysical Profile (BPP)
A biophysical profile (BPP) is a non-stress test (NST) with an ultrasound. If the NST results are not reactive, a BPP may be done.
The BPP looks at the baby’s movement, body tone, breathing, and the results of the NST test. The BPP also looks at amniotic fluid, the liquid that surrounds the baby in the uterus.
The BPP test results can be normal, abnormal, or unclear. If the results are unclear, you may need to repeat the test. Results that are not normal may mean that the baby needs to be delivered early.
Modified Biophysical Profile (MBPP)
A modified biophysical profile (MBPP) is also a non-stress test (NST) with an ultrasound. This test looks only at how much amniotic fluid there is. The MBPP test takes less time than a BPP. Your doctor may feel that the MBPP test will be enough to check the baby’s health, without doing a full BPP.
In a healthy pregnancy, these tests may not be done. But if you have medical problems, the potential for pregnancy problems (“high risk pregnancy”), or have gone a week or more past your due date, you may need some of these tests. Talk to your doctor about the tests and what the results mean for you and your baby.
Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.