Pregnancy & Baby Index: Pregnancy - Health and Wellness: Prenatal Testing: Contraction Stress Test
Contraction Stress Test
Many women undergo tests during pregnancy to check for birth defects, genetic disorders, and other problems. Find out more here about the contraction stress test (aka the "oxytocin challenge test" or simply "stress test"), used in the third trimester to check how the baby is reacting to life in the womb.
What it is
Labor represents a stress to the fetus. Every time the uterus contracts, the fetus is momentarily deprived of its usual blood supply and oxygen. While this is not a problem for most babies, however, some babies are not healthy enough to handle the stress and demonstrate an abnormal heart rate pattern. This test is often done if the
non-stress test (NST) is abnormal.
The procedure involves giving pitocin, a synthetic version the hormone oxytocin -- which is naturally secreted by every mother when normal labor begins -- to the mother to stimulate uterine contractions. The contractions are a challenge to the baby, similar to the challenge of normal labor.
If the baby's heart rate slows down rather than speeds up after a contraction, the baby may be in jeopardy.
The contraction stress test is considered more accurate than the non-stress test. Nevertheless, it is not 100 percent foolproof, and your caregiver may want to repeat it on another occasion to ensure its accuracy.
But will it hurt? Most women describe this test as mildly uncomfortable but not painful.
Just how helpful can these tests be? Here's what one mom-to-be had to say: "When I went for my weekly appointment on his due date and the doctor put on the fetal monitor, she was concerned that the baby's heart rate was dropping slightly during the mild contractions that I was having at this point. The doctor asked me to come to the hospital the next day for a stress test to see how the baby would respond to slightly stronger contractions, and the result was the same -- the heart rate dropped. Therefore, to avoid a possible emergency c-section, the doctor decided to induce the next morning at 6:00am, and Spencer was born at 12:30pm."