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Electronic Fetal Heart Monitoring

Internal monitoring can be done only after your cervix has dilated to at least 2 centimeters (cm) and your amniotic sac has ruptured. Once started, internal monitoring is done continuously.

For internal monitoring, a sensor is attached to your thigh with a strap. A thin wire (electrode) from the sensor is inserted through your vagina and cervix into your uterus. The electrode is then attached to your baby's scalp. Your baby's heartbeat may be heard as a beeping sound or printed out on a chart. Internal monitoring does not use reflected sound waves (ultrasound) for monitoring.

A small tube that measures uterine contractions may be placed in your uterus next to your baby. The strength and timing of your uterine contractions is usually printed out on a chart.

Internal monitoring is more accurate than external monitoring for keeping track of your baby's heart rate and your contractions.

Why It Is Done

External fetal heart monitoring

External fetal heart monitoring is done to:

  • Keep track of your baby's heart rate.
  • Measure how often you have a contraction and how long your contractions last during labor and delivery.
  • Find out whether you are having preterm labor.
  • Check on your baby's health if problems are suspected. External fetal heart monitoring will be done during a nonstress test to check your baby's heart rate while at rest and while moving. If your baby does not move during this test, more testing will be needed.
  • Check on your placenta to make sure that it is giving your baby enough oxygen. A contraction stress test that shows that your baby is not getting enough oxygen helps your doctor make decisions about the safest delivery method. If the test shows that your baby may be in danger, your doctor may recommend starting (inducing) labor early or may talk to you about doing a cesarean section (C-section).
  • Check your baby's health if your baby has not been growing normally (delayed fetal growth) or if you have diabetes or high blood pressure (hypertension) or if you are over 41 weeks pregnant.

Internal fetal heart monitoring

Internal fetal heart monitoring is done to:

  • Find out if the stress of labor is threatening your baby's health.
  • Measure the strength and duration of your labor contractions.

WebMD Medical Reference from Healthwise

Last Updated: January 14, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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