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For a 35-year-old expectant mother from Mumbai, Preeti, it was stressful when she could not feel fetal movement during her 7th month for a long period. While she was rushed to a hospital, she was made to undergo a Non-stress Test (NST) to analyze the fetus’s health. The test was a life-saving intervention as the doctors found that the baby’s umbilical cord was strangling the neck and she required an immediate delivery. She delivered a girl baby in the 28th week.
While a series of screenings are conducted during pregnancy to ensure the mother and fetus’s health, a nonstress test is one of the crucial tests done especially in high-risk pregnancies. This test is done to measure the heart rate of the growing fetus when the baby moves inside the uterus. It is done to check the overall well-being of the baby.
When is the nonstress test taken?
The prenatal test gets its name for being non-invasive and ensuring that there is no stress on the baby. NST takes place during the 28-30 weeks of the pregnancy cycle — the fetal movement and heart rate are monitored when it moves around the womb. “When we perform a rigorous activity, our heart rate increases. Similarly, the baby’s heart rate will increase when there is any sort of movement. This is what the NST follows,” says Dr Suruchi Desai, Senior Consultant, Obstetrics and Gynaecology, Nanavati Max Super Speciality Hospital, Mumbai.
Dr Desai, who delivered Preeti’s baby recalls that, despite repeating non-stress test, for more than two days, it was found that the baby was in a concerning position. “We had an immediate C-section for her and luckily the baby was delivered fine,” she says.
NST helps mothers with high-risk pregnancy
According to Dr Sophia Rodrigues, Consultant Obstetrician & Gynaecologist, Manipal Hospital, Panjim, Goa, not every pregnant woman is required to undergo NST. It is a recommended prenatal test only if the mother is undergoing a high-risk pregnancy. “High-risk pregnancy mothers can be classified as the ones who have existing medical conditions like diabetes, high blood pressure, and so on,” she says.
Other probabilities of when the nonstress test will be required according to experts are –
- Post IVF pregnancy
- Autoimmune diseases
- Pregnancy after cancer treatment
- Pregnancy after a kidney transplant
- Pregnancy post-liver transplant
- Miscarriages in the past
- Late pregnancies (post 35 years)
Apart from these conditions, NST is conducted when the concerns about fetal growth and amniotic fluid levels in the womb rise. “If there is fetal growth problem or if the water level in the baby’s water bag is low, NST is done,” Dr Rodrigues says. In some cases, the test is done every two weeks or even weekly, to ensure the baby’s wellbeing, she adds.
How is the NST test performed
NST is performed in the labor room for about 20 to 30 minutes and the mechanisms are similar to that of an electrocardiogram (ECG) test. “A gel is applied on the belly of the mother and she is strapped with two belts — one to monitor the fetal heart rate and the other to read contractions,” says Dr Desai. “The mother will be given a marker that she will have to press every time the baby moves. The marker records the acceleration of the heart rate and the fetal movement, which can be visible on the graph displayed in the monitor,” she adds.
Reactive and non-reactive results: What to conclude
The results of the nonstress test are concluded as reactive and non-reactive. “A baby is considered to be reactive if there is an increased heart rate during fetal movement, i.e, acceleration has to be from more than 15 beats per minute,” says Dr Rodrigues. “A non-reactive result is when there is no acceleration in the baby’s heart rate or cannot record any movement at all. Such cases take place when the baby is asleep during the test, upon which we would advise the mother to repeat the test after eating food. However, not all non-reactive results are a red flag, it means further investigation is required,” she adds.
Takeaways
- A nonstress test is a prenatal and non-invasive test to record the fetal heart rate and movement and to understand the overall well-being of the baby.
- It is done during 28 to 30 weeks of pregnancy and the test can last for 20-30 minutes.
- Non-stress test is recommended for mothers who are undergoing high-risk pregnancies to ensure timely intervention and save the mother and baby.
