3. DEFINITION
Non-stress test is a simple, painless procedure in which a baby's
heartbeat is continuously monitored for 20 minutes or more and
the details are recorded for evaluation.
The fetal Non-Stress test is a simple, non-invasive test
performed in pregnancies over 28 weeks gestation. The test is
named “non-stress” because no stress is placed on the fetus
during the test.
The logic behind the test is, that like adults, a baby's heart beat
should accelerate when it is active i.e. moving and kicking.
The non-stress test can be done whenever the need arises so
there is no specific time for it.
4. Who needs the non-stress
test :-
Women with pre-existing medical conditions such
as diabetes
Women with pregnancy-induced medical
conditions such as hypertension
Baby is less active than normal
Baby is small for its age
Amniotic fluid is either too much or too little
Women who have previously lost their babies in
the second half of their pregnancies
Women with pregnancies continuing after week 40
to basically check on the well- being of baby.
5. Procedure
The test involves attaching one belt to the mother’s abdomen to measure fetal heart rate and another belt
to measure contractions. Movement, heart rate and “reactivity” of heart rate to movement is measured for
20-30 minutes. The test takes about 20 minutes to an hour.
If the baby does not move, it does not necessarily indicate that there is a problem; the baby could just be
asleep. A nurse may use a small “buzzer” to wake the baby for the remainder of the test
It will be sensible to pee and tuck in a snack before the procedure as the whole thing can last for an hour.
Sometimes little ones don't cooperate during the testing and move. So the mother is offered a drink of
something usually containing sugar or bubbles to perk the baby up. If this doesn't cause the baby to move
sometimes a loud sound will be used to startle the baby into moving. Remember babies can and do sleep
in utero.
6. When is a NST performed :-
NSTs are generally performed after 28 weeks of gestation. Before 28 weeks, the fetus is
not developed enough to respond to the test protocol.
7. What does the NST look for :-
The primary goal of the test is to measure the heart rate of the
fetus in response to its own movements. Healthy babies will
respond with an increased heart rate during times of movement,
and the heart rate will decrease at rest. The concept behind a
non-stress test is that adequate oxygen is required for fetal
activity and heart rate to be within normal ranges. When oxygen
levels are low, the fetus may not respond normally. Low oxygen
levels can often be caused by problems with the placenta or
umbilical cord.
8. Interpretation & Results
The test result is considered to be normal or reactive if
baby's heart beats faster on two separate occasions
during the 20 minute span.
If baby is resting the result will most likely be non-
reactive. However if results persist to be non-reactive
even after one hour, it doesn't necessarily mean
something is wrong with the baby.
Results may also be non-reactive due to baby's age;
babies below week 32 have not hit the required
maturity for reactivity.
The test time may be extended or the mother may
have to go for more comprehensive tests like
biophysical profile.
If the doctor is absolutely sure that baby is not thriving
inside, the labor may be induced.
9. ROLE OF NURSE:-
Nurse helps in the preparation of the mother and in counseling the parents when
findings are revealed.
Nurse should involve in giving simple explanation of measurements and gestational age
to offering support and advice when an abnormality is formed.
Nurse should apply their obstetric knowledge in interpreting the test if they are trained.
Nurse should give findings to the mother immediately which eliminates the anxiety
caused by delay.
Many questions may be asked by the parents after detection of any abnormality, in such
cases the nurse should deal with it patiently.
The nurses should keep themselves up to date on the latest prenatal diagnosis, the
treatment available and the possible outcomes of such pregnancies.
