A nonstress test is often used to assess a fetus’s health. For the duration of the test, the fetus’ heart rate is examined and observed. This is to see how the heart responds to the baby’s movements within the uterus. The test is referred to as nonstress as no stress is applied on the baby throughout the diagnostic observation.
Why Is a Nonstress Test Performed?
Usually, a nonstress test is done when a fetus’s mortality rate increases or it is at risk of being miscarried or still birthed. The test is done usually after 26 to 28 weeks of gestation. A negative outcome in a nonstress test can help indicate whether the mother and baby need further testing.
The nonstress test helps monitor both the heart rate and oxygen supply of the fetus. Typically, a fetus’ heart beats a lot faster when they are active in the last trimester. However, in the presence of hypoxia – lack of oxygen supply – this reaction may be altered.
Your provider may recommend you undergo a nonstress test if you have:
- A pregnancy with multiple fetuses
- An underlying medical condition including but not limited to hypertension, heart disease, or diabetes
- A pregnancy that has gone beyond the due date
- Complications in current or previous pregnancies
- A fetus with decreased movement or growth issues
- Rhesus (Rh) sensitization – a potentially dangerous condition that is caused by the mother being Rh negative and the fetus being Rh positive
- Low levels of amniotic fluid
A nonstress test can be performed anywhere from once or twice a week to everyday, depending on the health of the mother and baby.
At first, our healthcare professionals will take some vitals such as your blood pressure. During your test, you will be sitting in a chair that is reclined slightly. Throughout the course of your test, your blood pressure will be measured at intervals. A sensor will be wrapped around your abdomen to determine the fetal heart rate. Most nonstress tests last around twenty minutes. However, in the case the fetus may be inactive, it may stretch to another twenty minutes waiting for the fetus to become more active. To stimulate the baby, some devices that cause noise may be used.
The result of the test could either be reactive or nonreactive. In the case of reactive, the baby’s heart rate increases twice or more above the baseline value for ten seconds during the test at less than week 32. When the fetus is more than 32 weeks, the heart rate increases twice more than the baseline for fifteen seconds.
Contrastingly, in a nonreactive test result, the heart rate does not increase to the threshold required. This result is not always due to possible abnormality. It can even be caused if the baby was asleep. To further keep the fetus’ health in check, more prenatal tests may be done, such as a biophysical profile or a contraction stress test.
Many conditions or habits may cause a baby to exhibit nonreactive behavior, such as fetal hypoxia, smoking, certain medications, cardiac anomalies, and neurologic anomalies in the fetus. The test results should be discussed with one of our providers, so that we can make sure to take appropriate steps to keep both you and your baby safe.
Fetal Nonstress Tests in Cook County, IL
For more information, call Women’s HealthFirst at (847) 808-8884 or request your appointment now. We have five locations near Chicago, Illinois, to serve you. Established patients are encouraged to visit the convenient online patient portal to request an appointment, message our team, update their records, and more.