Antepartum Testing

Your doctor may request antepartum testing starting between weeks 32 and 34 if you or your baby needs special monitoring. Special concerns that warrant antepartum testing in pregnancy include:

• Having a preexisting health condition such as diabetes or heart disease
• Pregnancy-related high blood pressure (preeclampsia)
• Having had previous miscarriages or stillbirths
• Other test results that have indicated a concern, such as a growth problems or Rh sensitization
• Decreased movement of the fetus
• Pregnancy that goes past 41 weeks (post-term pregnancy)
• Carrying twins or higher multiples with certain complications

There are six commonly used antepartum tests that your doctor may use in varying combinations to monitor the health of your baby leading up to birth. All are non-invasive and comfortable. You may have the tests more than once (weekly or even bi-weekly) depending on your doctor's recommendations.

At this point in your pregnancy, your baby can be delivered through induced labor, but research indicates that babies that are delivered at full-term (40 weeks) have certain health benefits. The goal of antepartum testing is not to find a reason to deliver early but to monitor you and your baby to make sure that an early delivery is only used if there is a serious concern that warrants it.

The Six Antepartum Monitoring Tests

Most women who need antepartum testing have the first two tests on this list. The last four are included if there is a special concern your doctor wants checked.

Non Stress Test (NST)

The NST involves placing a belt with a fetal monitor around your abdomen for 20 minutes. The monitor records the fetal heart rate and uterine contractions so that your doctor can check if your baby’s heart is periodically accelerating (speeding up) in a normal pattern. If the heart rate does not accelerate, your doctor may leave the monitor in place for an additional 40 minutes and/or stimulate the baby with sound. Often, the heart rate not accelerating as expected is simply because your baby is napping. However, it can also mean there is a problem, such your baby having a reaction to a medication you may have taken or that your baby is not getting enough oxygen.

Amniotic Fluid Index (AFI)

The AFI measures the depth of the amniotic fluid pockets surrounding your baby using an ultrasound machine. Not enough amniotic fluid will mean more close monitoring and, if the fluid level is dangerously low, early delivery.

Biophysical Profile

If additional information is needed beyond checking the baby’s heart rate and the amount of amniotic fluid, your healthcare provider will score a series of observations made during the NST and AFI. Five elements (fetal heart rate, fetal body movements, fetal muscle tone and amniotic fluid amount) are scored from 0 to 2 for a possible total of 10. A score of 8 or above is reassuring. A score of 6 to 8 is equivocal (neither reassuring nor concerning) and a second biophysical profile will typically be done within the next 12 to 24 hours. Depending on how far along your baby is, your doctor may also recommend that your baby be delivered. A score of 4 or less means more testing is needed and sometimes your doctor must deliver your baby right away. A biophysical profile does not measure fetal size, determine gender or diagnose fetal conditions.

Oxytocin Contraction Stress Test

This test is similar to the breast stimulation stress test. Instead of producing mild uterine contractions through breast stimulation, your healthcare provider will give you an intravenous or IV infusion of Pitocin, a drug that contains a synthetic form of the natural contraction-inducing hormone oxytocin. You may need Pitocin if you have no spontaneous contractions in response to breast stimulation.

Doppler Ultrasound of the Umbilical Cord Artery

Using an ultrasound machine to visualize the umbilical cord artery lets your doctor check if poor blood flow may be the cause of a previous concerning test result or problems with fetal growth.

What to Expect

Antepartum tests typically take 30 to 45 minutes to complete. Have a beverage, snack or meal just prior to your antepartum tests as your baby may be more active if you have recently eaten and are well-hydrated. The tests are done while you lie on your back on an exam table. There is some quiet waiting time as data is collected so bringing something to read to entertain yourself can make time pass more quickly.