Fetal Non-Stress Test (NST)
A fetal non-stress test (NST) is a type of examination used to measure the activity of a fetus. The primary purpose of a fetal non-stress test is to gain insight into the fetus’ regular movements and heart rate to determine whether these are developing normally.
This test is non-invasive, only requires 20-30 minutes to complete, and is entirely safe for both mother and baby. No known side effects currently exist for a fetal NST.
Reasons for a Fetal Non-Stress Test
There are several situations in which a fetal non-stress test would be advised, including instances when:
- The mother is overdue
- The pregnancy is already high risk
- There is reason to suspect that the placenta is not functioning appropriately
- The fetus does not appear to be as active as they should be
What to Expect During a Fetal NST
The expectant mother must be over 28 weeks pregnant in order to perform a fetal non-stress test since the fetus must develop significantly before conclusive results can be drawn.
Two types of belts are placed around the mother’s abdomen during the exam. One belt measures the fetal heart rate while the other measures contractions.
By assessing these metrics, the doctor can determine whether or not the baby’s heart rate corresponds appropriately to their movements. Normally, the fetus’ heart rate will increase while they are active, and will decrease during periods of rest.
Low heart rate and immobility can be a sign that the fetus is not getting enough oxygen. These low oxygen levels are often caused by some sort of damage to the placenta or umbilical cord.
If abnormal activity rates are found during the fetal non-stress test, South Florida Women’s Care is likely to order additional tests to determine the exact cause of these conditions. On occasion, low heart rate reactivity during a non-stress test can merely be a result of the baby’s sleeping habits or maternal medicines within the mother’s system.