Based on the results of routine prenatal care, your health
care provider may suggest further tests to assess the health
of the fetus.
Some of these further tests and monitoring may be done with electronic equipment.
Fetal monitoring detects signs of some problems as early as possible in pregnancy. Although
this testing can provide valuable information, normal results do not guarantee
a healthy baby. All pregnancies carry some degree of risk, and monitoring does
not remove that risk. But it does help your health care provider to take better
care of you and your baby during your pregnancy.
How Does Monitoring Work?
Special
Tests:
How
Does Monitoring Work?
Some of
the tests used for monitoring check the fetus's movement,
heartbeat, and rate of growth. Some tests show an image of
the fetus in the uterus.
Others create a sound or recording of the fetus's heartbeat.
Your health care provider may combine these tests to capture
both sounds and images.
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Special
Tests
Five tests may be used to monitor the well-being of the fetus before birth:
- Kick
count
- Ultrasound
- Nonstress
test
- Biophysical
profile
Kick
Count
Not all tests require special equipment. For instance, you can monitor
your fetus's movements yourself by keeping a kick count in late pregnancy.
To record a kick count, you simply note the number of times the fetus
moves over a certain period. Your health care provider can tell
you when and how to perform this test and what the results might mean. If
you do not feel the fetus does not move in a 12-hour period, let your
health care provider know.
Ultrasound
Ultrasound is a test in which pictures (called sonograms) of the fetus are
created from sound waves. It is used in almost every major hospital and
in many health care providers' offices. From these pictures, your health
care provider can learn about the fetus and its health.
A small device called a transducer is used to perform an ultrasound exam.
Your health care provider will use either a hand-held transducer, which is
moved along the mother's abdomen, or a vaginal transducer, which is placed
in the vagina. The transducer sends out waves that are echoed back from the
fetus. These waves are then turned into an image of the fetus on a monitor.
Doppler ultrasound uses
sound waves to create a signal of the fetal heartbeat. In this case, the
sound waves are reflected back in the form of signals of the fetus's heartbeat.
These are shown on a graph rather than in the form of pictures.
Ultrasound can be used alone or can be combined with other tests to provide
information on the fetus's growth and health. No harmful effects to either
the mother or the fetus have been found in over 20 years of use of this test,
although the effects of ultrasound are still being studied. The long-term
risks of ultrasound, if any, are unknown, but there are many benefits.
Nonstress
Test (NST)
The nonstress test (NST) measures the fetus's heart rate in response to the
movements of the fetus. Usually, the fetus's heart beats faster when the
fetus moves.
This test
is based on the movements of the fetus. A belt is placed
around the mother's waist. Transducers are attached to the
belt. The test usually takes 20-40 minutes. During that time
the fetus's heart rate patterns are measured by Doppler ultrasound. The
mother presses a marker button each time the fetus moves,
or the fetus's movements may be noted by a health care provider
or nurse. A record of the fetus's heart rate is made on graph
paper.
Sometimes the fetus will not move for a short time during the NST (perhaps
as long as 40 minutes). This does not necessarily mean that there is a problem: most
likely, the fetus is asleep or resting. If this happens, your health care
provider or nurse may try waking the fetus with a buzzer or by having you
eat or drink.
Sometimes
the results of an NST suggest that there is a problem, when
in fact the fetus is healthy. If the nonstress test shows
no change in the fetal heart rate in response to fetal movement,
your health care provider will probably want to do another
test to find out whether the results of the NST are correct.
Biophysical
Profile (BPP)
The biophysical profile (BPP) combines an ultrasound exam with an NST to
give a limited physical exam of the fetus. Usually, five factors are studied:
-
Heart
rate (using the NST)
-
Fetal
breathing
-
Fetal
body movement
-
Fetal
muscle tone
-
Amount
of amniotic
fluid
Each
of these items is scored, and the total is added. The test
may be repeated, if needed. Your health care provider may
use the score obtained from the BPP to decide whether you
need special care or whether your baby should be delivered
early.
Who
Should Get Special Tests?
Depending
on the stage of your pregnancy, your history, and the results
of routine tests, your health care provider may advise that
you have more tests to check the growth and health of the fetus.
Women who have a higher risk of having problems during pregnancy because of
a medical condition need more monitoring than other women. Some of the conditions
that may signal a need for regular prenatal testing include:
- High
blood pressure
- Diabetes
- Postterm
pregnancy (pregnancy that lasts more than 2 weeks
past the due date)
- Too
much or too little amniotic
fluid, as shown by ultrasound
- Kidney
or heart disease
- Multiple
pregnancy (two or more fetuses)
Ultrasound,
the NST, and the BPP provide useful information that will help
your health care provider decide what treatment is best for
you. The goal is to keep you and your baby as healthy as possible.
Monitoring
helps you and your health care provider throughout your pregnancy
by giving important information about the well-being of the
fetus. If a test result suggests that there may be
a problem, this does not always mean that the fetus is in
trouble. It may simply mean that you need special care. Discuss
any questions you have about monitoring when you talk with
your health care provider during your regular visits for
prenatal care.
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