What does a nonstress test (NST) primarily assess in pregnant women?

A nonstress test (NST) primarily assesses the fetal heart rate response to fetal movement. This test is performed during pregnancy to monitor the well-being of the fetus, particularly when there are concerns about the baby's health or if the mother has certain risk factors. The NST involves placing sensors on the mother's abdomen to track the fetal heart rate and any accelerations that occur in response to fetal movements.

During the test, healthcare providers look for accelerated heart rate patterns, which indicate that the fetus is well-oxygenated and responding appropriately to movement. A positive response usually signifies that the fetus is healthy and not in distress. This makes the assessment of the fetal heart rate in relation to movement a vital indicator of the baby's well-being.

Other options, such as evaluating breathing movements, body movements, or fetal body tone, while relevant to overall fetal health, are not the primary focus of the NST. These other assessments may be conducted through different types of fetal monitoring or ultrasound examinations, but they do not specifically evaluate the heart rate response to movement as the NST does.