Electronic Fetal Heart Monitoring
Why It Is Done
External fetal heart monitoring is done to:
- Keep track of your baby's heart
- Measure how often you have a contraction and how long your
contractions last during labor and delivery.
- Find out whether you
- 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
- 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
high blood pressure (hypertension), or are over 41
Internal fetal heart monitoring is
- Find out if the stress of labor is
threatening your baby's health.
- Measure the strength and duration
of your labor contractions.
How To Prepare
You may be asked to eat a meal shortly
before having a nonstress test, because digesting food often increases the
movement of your baby.
If you are having a contraction stress
test, you may be asked to not eat or drink for 4 to 8 hours before the
If you smoke, you will be asked to stop smoking for two
hours before the external monitoring test because smoking decreases your baby's
How It Is Done
External monitoring can be done any
time after 20 weeks of pregnancy. Internal monitoring is used only when you are
in labor and your amniotic sac has broken. If internal monitoring is needed and
your amniotic sac has not broken, your doctor may break the sac to begin the
test. Sometimes a combination of internal and external monitoring is done by
measuring your baby's heart rate with an internal sensor and measuring your
contractions with an external sensor.
For external monitoring, you
will usually lie on a table on your back or left side. Two belts with sensors
attached will be placed around your belly. One belt holds the sensor that keeps
track of your baby's heart rate, while the other measures the timing and
strength of your uterine contractions. Gel may be applied to provide good
contact between the heart rate sensors and your skin. The sensors are attached
with wires to a recording device that can indicate or print out a record of
your baby's heart rate as well as the strength and duration of uterine
contractions. The position of the heart rate monitor may be changed
periodically to adjust to the movement of your baby.