Measuring Baby's Heart Rate to Prep for Labor

Preparing Your Baby for Labor

During your pregnancy, there might be reasons to test your baby’s reaction to labor. The tests are designed to measure your baby’s heart rate during stress, so you and medical professionals can better prepare for the little one’s entrance into the world.

There are three main tests used to measure your baby’s heart rate: fetal nonstress test, biophysical profile, and contraction stress test. All of these tests are completed after 28 weeks gestation. The results will help decide your baby’s needs during birth.

Fetal Non-stress Test

Your obstetrician might recommend a fetal non-stress test for the following reasons.

• The baby is not moving as often as usual.
• You are overdue.
• The placenta might not be functioning properly.
• Your pregnancy is high risk.

The test determines if your baby’s heart responds properly to movement. In healthy babies, heart rate increases with movement and decreases during rest. The test allows your doctor to see if the baby has enough oxygen for normal fetal activity.

A non-stress test takes 30 minutes to an hour. You will wear two monitors: one to watch the baby’s heart rate and the other to record contractions of your uterus. A technician will watch your baby’s heart rate on a monitor throughout the test.

If your baby isn’t moving, he or she might be asleep. In this case, the technician will ask you to drink juice or water and may use a buzzer next to your belly to wake the baby. You might be asked to press a button when you feel the baby move.

If your baby’s heart rate increases during movement, the test is considered reactive or normal. You might be asked to repeat the test later in the pregnancy as well. If the baby’s heart rate doesn’t respond to movement or they don’t move within 90 minutes, the test is considered nonreactive. You will likely need further testing to determine a result.

Biophysical Profile

You might need a biophysical profile if you had a nonreactive fetal non-stress test. There are other reasons your doctor might schedule the test as well.

• You have gestational diabetes or hypertension.
• Your baby appears to be small or not growing properly.
• You are overdue.
• You have previously lost a baby during pregnancy.
• Your baby has a condition that needs to be monitored.

A biophysical profile combines a non-stress test with an ultrasound. The complete test may take 30 minutes to over an hour. A non-stress test will be performed to measure heart rate and movement, and an ultrasound will be performed to check your baby’s breathing, muscle tone, movement and amniotic fluid levels.

The test is scored on five sections, with a possible two points in each for a total score potential of 10 points. These sections are considered in the test:

• heart rate
• breathing
• muscle tone
• body movement
• amount of amniotic fluid

Scores lower than eight will usually require a retest. A very low score might mean your baby is in distress, and early delivery might be required.

Contraction Stress Test

A contraction stress test is usually done if you had an abnormal non-stress test or biophysical profile. The test works to see if your baby can handle the stress of contractions. During a contraction, blood flow and oxygen slow down. This is usually okay for your baby since the placenta has a reserve of oxygen. The test will observe your baby’s heart rate to ensure your placenta is working properly.

A contraction stress test takes about two hours. During the test, you will have two belts placed around your belly. One measures contractions and the other measures your baby’s heart rate. Contractions will be induced with oxytocin or nipple stimulation. The contractions might be uncomfortable.

If your baby’s heart rate stays normal throughout the test, your results are considered normal. Your doctor might still request a repeat of this test later in the pregnancy. If your baby’s heart rate drops during contractions, he or she may be under stress. Your doctor might decide the baby should be born right away by cesarean section or by induction.

A contraction stress test is the least performed of these tests, since you might get a false negative result or the stimulation of contractions can result in preterm labor.

These three tests are not always required during pregnancy, but your doctor knows how to ensure the best health of your baby. Pregnancy carries different risks for each family, and it is important to periodically and frequently measure your baby’s health.