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Pregnancy Weeks 38-Birth - Page 8

Healthy Pregnancy Newsletter
Healthy Pregnancy Newsletter - Checking It Out

Listening to your unborn baby's heartbeat

In late pregnancy and during labor, your doctor or midwife may want to monitor your unborn baby's heart rate and other functions. Fetal heart rate monitoring is a method of checking the rate and rhythm of the fetal heartbeat. The average fetal heart rate is between 110 and 160 beats per minute. During labor, the fetal heart rate may be checked regularly with a hand held Doppler device like the one used at your prenatal visits. Continuous electronic fetal monitoring is sometimes used.

Here's how monitoring generally works:

  • Gel is applied to the mother's abdomen to act as a medium for the ultrasound transducer.
  • The ultrasound transducer is attached to the abdomen with straps and transmits the fetal heartbeat to a recorder. The fetal heart rate is displayed on a screen and printed onto special paper.
  • During contractions, an external tocodynamometer (a monitoring device that is placed over the top of the uterus with a belt) can record the patterns of contractions.
  • Sometimes, internal fetal monitoring is necessary for a more accurate reading of the fetal heart rate. Your bag of waters (amniotic fluid) must be broken and your cervix must be partially dilated to use internal monitoring. Internal fetal monitoring involves inserting an electrode through the dilated cervix and attaching the electrode to the scalp of the fetus, called a fetal scalp electrode.

The fetal heart rate may change as the fetus responds to conditions in the uterus. An abnormal fetal heart rate or pattern may mean that the fetus is not getting enough oxygen or there are other problems. An abnormal pattern also may mean that an emergency or cesarean delivery is needed.

Why are some labors induced?

Most women give birth between 37 and 41 weeks of pregnancy. While it's usually best to let nature take its course, in some cases, labor has to be "induced." This is a process of artificially stimulating labor to begin.

Some reasons for induction include:

  • Situations in which the mother and/or her unborn baby are at risk
  • The pregnancy has continued too far past the due date
  • The mother has high blood pressure of pregnancy
  • Poor growth of the unborn baby
  • Premature rupture of the membranes (bag of waters has broken early)

In an induction, medications or artificial methods are used to start and stimulate the natural process of labor. These are used to make the uterus contract and the cervix dilate and efface.

Some common techniques of induction include the following:

  • Inserting vaginal suppositories that contain the hormone prostaglandin to stimulate contractions
  • Administering an intravenous infusion of oxytocin (a hormone produced by the pituitary gland that stimulates contractions) or similar drug
  • Rupturing (artificially) the amniotic membranes (bag of waters)

Your doctor or midwife can advise you on whether your labor needs to be induced.

Nonstress Testing

A nonstress test (NST) measures the fetal heart rate in response to the fetus' movements. Generally, the heart rate of a healthy fetus increases when the fetus moves. The NST is usually performed in the last trimester of pregnancy in a special prenatal testing area of the hospital, or in your doctor's office. The NST uses continuous electronic fetal monitoring to record the fetal heart rate. The mother is instructed to push a button on the monitor each time she feels fetal movement. This places a mark on the paper printout. The NST usually lasts for 20 to 40 minutes. Test results of the NST may be reactive (normal), when there are two or more fetal heart rate increases in the testing period, or nonreactive, when there is no change in the fetal heart rate when the fetus moves. This can occur when the fetus is asleep, or when a fetus is too young or it may mean that there is a problem that requires further testing.


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