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Electronic Fetal Heart Monitoring

How It Is Done continued...

For a nonstress test, the sensors are placed on your belly. You may be asked to push a button on the machine every time your baby moves or you have a contraction. Your baby's heart rate is recorded and compared to the record of movement or your contractions. This test usually lasts about 30 minutes.

Internal monitoring

For internal monitoring, you will usually lie on a bed on your back or left side. A thin wire (electrode) will be guided through your vagina and cervix and attached to your baby's scalp. A small tube is also inserted through your vagina to connect a device that monitors the contractions inside your uterus. A belt is placed around your upper leg to keep the monitor in place. The electrode and the tube are attached with wires to a recording device that can show or print out a record of your baby's heart rate as well as the strength and duration of your uterine contractions.

How It Feels

Lying on your back (or side) while you are being monitored may be uncomfortable or painful if you are having labor contractions. The belts holding the monitors in place may feel tight.

You may be able to change positions or move around more during internal electronic fetal heart monitoring than during external monitoring.

Placing the internal monitor into your uterus may be mildly uncomfortable.

Risks

Studies show that electronic fetal monitoring may be linked to an increase in cesarean deliveries and in the use of a vacuum or forceps during delivery.1

There is a slight risk of infection for your baby when internal monitoring is done.

Results

Electronic fetal heart monitoring is done during pregnancy, labor, and delivery to keep track of the heart rate of your baby (fetus) and the strength and duration of the contractions of your uterus. The results of electronic fetal heart monitoring are usually available immediately.

Electronic fetal monitoring
Normal:

Your baby's heart rate is 110 to 160 beats per minute.

Your baby's heart rate increases (accelerates) when he or she moves and when your uterus contracts.

Your baby's heart rate drops during a contraction but rapidly returns to normal after the contraction is over.

Uterine contractions during labor are strong and regular.

Abnormal:

Your baby's heart rate is less than 110 beats per minute.

Your baby's heart rate is more than 160 beats per minute.

During a nonstress test, your baby's heart rate does not increase by 15 beats per minute or drops far below its baseline rate (deceleration) after he or she moves.

Uterine contractions are weak or irregular during labor.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Smoking cigarettes or using other tobacco products and drinking or eating large amounts of caffeine (such as from several cups of strong coffee), which can falsely raise your baby's heart rate.
  • Extra noises such as your heartbeat or your stomach rumbling.
  • Your baby is sleeping during a nonstress test.
  • Problems with the placement of the external monitoring device. These problems may include:
    • Your baby is moving a lot during the test.
    • You are pregnant with more than one baby, such as twins or triplets.
    • You are overweight.

WebMD Medical Reference from Healthwise

Last Updated: June 18, 2012
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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