A non-stress test (NST) is a common, non-invasive screening tool used during pregnancy to check on the baby’s health. It’s often recommended for women who are overdue, have had complications during pregnancy or childbirth, or if the baby isn’t moving as much as expected. The test focuses on monitoring the baby’s movements, heartbeat, and any contractions to ensure they’re receiving enough oxygen and are in good health.
The test involves lying down while two belts are placed around the belly—one tracks the baby’s heartbeat, and the other detects any uterine contractions. The mother may press a button when the baby kicks or moves to help monitor how the heartbeat reacts to movement. Typically, the test lasts around 20 minutes, but if the baby is sleeping, nurses may try to wake them by gently shaking the belly or using sounds. A healthy, active baby’s heart rate usually increases during movement. If the results don’t seem normal, further testing may be required.
NSTs are generally recommended for high-risk pregnancies or after 28 weeks of gestation, as the test isn’t reliable earlier. Women with conditions like gestational diabetes, high blood pressure, or past pregnancy complications may need weekly or bi-weekly NSTs. The test is also essential if there’s reduced fetal movement, concerns about the baby’s growth, or if the pregnancy goes beyond 40 weeks.
This procedure is safe for both the baby and the mother, as it doesn’t involve any invasive methods or medications. Even if the NST shows nonreactive results—which means the baby’s heartbeat didn’t accelerate as expected—it doesn’t always indicate a problem. It could be due to the baby sleeping or other minor factors. In such cases, the doctor may recommend repeating the test, performing a biophysical profile, or conducting additional tests to gather more information.
There are alternatives to the NST, such as the biophysical profile, which combines the NST with an ultrasound to check amniotic fluid levels, baby’s movements, breathing, and muscle tone. A modified biophysical profile is a quicker version that specifically measures amniotic fluid levels. These tests are usually ordered if the NST results are unclear or nonreactive.
The main goal of the NST is to provide insights into how the baby’s heart reacts to activity, which reflects their overall health. A normal heart rate for a fetus ranges between 110 and 160 beats per minute. If the heart rate varies appropriately with movement, it’s a reassuring sign that the baby is receiving sufficient oxygen and is generally healthy. Minimal variation, however, could indicate potential issues, such as lower oxygen levels or difficulties responding to their environment.
Doctors recommend NSTs in several scenarios: if the baby isn’t moving as much as usual, if there’s a risk of placental issues, or if other complications like preeclampsia or gestational diabetes arise. The test may also be used to monitor the baby’s health during late pregnancy when the placenta begins to age, or physical conditions place additional demands on the baby.
Although NSTs are highly reliable and risk-free, occasional inconsistencies or unclear results could lead to follow-up tests. For example, if the test shows nonreactive results, and subsequent testing confirms issues like low oxygen levels or placental concerns, the doctor might suggest inducing labor or taking other medical steps. In most cases, however, a reactive NST result indicates the baby is doing well at that moment.
Ultimately, NSTs are an essential tool for tracking a baby’s well-being in the later stages of pregnancy, especially for women with high-risk conditions or overdue pregnancies. They offer valuable reassurance to both doctors and parents, ensuring the baby is receiving adequate oxygen and is thriving in the womb. It’s always important to discuss any concerns or questions with your healthcare provider, who can guide you through the process and determine the right testing schedule based on your specific situation.