Fetal Testing: Checking How Your Baby Is Doing Before Birth

What Is Fetal Testing?

Fetal testing means checking how your baby is doing before birth. These tests look at your baby’s heart rate, movement, and fluid. They do not hurt you or your baby.

These tests do not treat a problem, but they can help you and your care team decide if you and your baby need closer watching or an earlier birth.

Why is Fetal Testing Recommended?

Your provider will recommend fetal testing if:

• You have a high-risk pregnancy (for example, if you have high blood pressure, diabetes, or another health condition)
• Your baby is measuring small or large for the number of weeks
• You feel your baby is moving less than usual
• You are past your due date
• There is too much or too little fluid around your baby
• You are carrying twins or more
• You had problems in a past pregnancy, such as a stillbirth
• There are concerns about the placenta or umbilical cord

What Tests May Be Done?

Fetal monitoring may include some or all of the following tests:

Non-stress Test (NST)

An non-stress test (NST) checks your baby’s heart rate. Non-stress tests can be done after 28 weeks of pregnancy, and are more common at the end of pregnancy.

During the test:

• You rest in a chair or bed
• Two soft belts go around your belly to hold two small monitors
  • One monitor listens to the baby’s heartbeat
  • The other checks for contractions

The test usually takes 20–40 minutes. 

The healthcare team looks to see if:

• Your baby’s heart rate is between 110–160 beats per minute.
• The heart rate goes up (acceleration) from time to time. That is called reactive, or reassuring. It’s a good sign that the baby is healthy and not feeling stressed.
• If there are no accelerations, the test is nonreactive. More testing or care may be needed if this happens.
• It goes down (deceleration). That can be a sign that the baby is feeling stressed. More testing or care may be needed if this happens.

A reactive NST usually means that your baby is healthy, but you may still need to do the test again later.

Amniotic Fluid Index (AFI)

An amniotic fluid index (AFI) measures the amount of fluid around your baby. This is done with an ultrasound on your belly.

• Warm gel goes on your skin and a small wand slides around on your belly to take pictures.
• The provider measures the pockets of fluid around your baby.
• Too little or too much fluid can be a sign that your baby needs closer watching.

A normal amount of amniotic fluid is an AFI score of between 5 and 25. If one large pocket of fluid is measured, that is also a normal AFI. If the AFI is normal that usually means the placenta is working well.

Biophysical Profile (BPP)

A biophysical profile (BPP) is a test that combines an NST and an ultrasound. It is like a “score card” for your baby. This is done with an ultrasound on your belly.

• Warm gel goes on your skin and a small wand slides around on your belly to take pictures.
• The care team looks at:
  • Your baby’s movement
  • Your baby’s muscle tone (how your baby flexes and stretches)
  • Your baby’s breathing motions
  • The amount of fluid around your baby

Each part gets a score. A higher score is more reassuring. A normal score is between 8 and 10.

Umbilical Artery Dopplers

Umbilical artery dopplers look at blood flow in the umbilical cord. This is recommended if your baby is small or has a health problem. This is done with an ultrasound on your belly. The wand makes a soft “whooshing” sound as it measures blood flow.

The test shows how easily blood moves between the placenta and your baby. If the blood flow is low or blocked, your team may watch you and your baby more closely. If the blood flow is normal, that is reassuring.