Electronic Non-Stress and Stress Testing

Non-Stress Test and Stress Test

Late in pregnancy, prior to the onset of labor, a fetal monitor may be used to determine the well-being of the baby and to help decide when a fetus should be delivered. This is most frequently used if a baby is past due or there are complicating medical conditions in the mother, such as high blood pressure, Rh disease, bleeding or kidney disease. It is also helpful in evaluating a fetus who is not growing properly, or whose fetal movement has significantly slowed down.

 The non-stress test (NST) is used to evaluate fetal heart rate patterns, especially during fetal movements. Increases in fetal heart rate are reassuring of fetal well-being, and the test is called reactive. A non-reactive test can be caused by medication or a sleeping fetus, and may require further testing.

 The contraction stress test (CST) will allow us to evaluate how the fetal heart reacts to uterine contractions. Certain fetal heart tracing characteristics occur in both healthy and unhealthy fetuses. The uterine contractions can be induced by a medication called oxytocin which is administered intravenously or by stimulation of the mother’s nipples (nipple stimu­lation test). The “stress” created by the contractions may reveal that the fetus is receiving a marginal blood and oxygen supply.

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