Why it's done

A biophysical profile is used to evaluate and monitor a baby's health. The goal of a biophysical profile is to prevent pregnancy loss and detect a low oxygen supply in the baby (fetal hypoxia) early enough so that the baby can be delivered and not sustain permanent damage.

The test is most commonly done when there's an increased risk of problems that could lead to complications or pregnancy loss. Your health care provider will determine the necessity and timing of a biophysical profile based on whether your baby could survive if delivered early, the severity of your condition and the risk of pregnancy loss.

Your health care provider might initially recommend a modified biophysical profile — a simplified version of the test that includes a nonstress test and assesses amniotic fluid through ultrasound. He or she will use the results to determine whether you need a full biophysical profile, which also measures a baby's breathing, movements and muscle tone, or other tests.

Your health care provider might recommend a biophysical profile if:

• You have a multiple pregnancy with certain complications
• You have a medical condition, such as diabetes, high blood pressure, lupus or heart disease
• Your pregnancy has extended two weeks past your due date (postterm pregnancy)
• You have a history of pregnancy loss or previous pregnancy complications
• Your baby has decreased fetal movements or possible fetal growth problems
• You have too much amniotic fluid (polyhydramnios) or a low amniotic fluid volume (oligohydramnios)
• You have rhesus (Rh) sensitization — a potentially serious condition that can occur when your blood group is Rh negative and your baby's blood group is Rh positive
• You are older than age 35
• You are obese

Your health care provider might also recommend a biophysical profile if you're between 40 and 42 weeks pregnant. The benefits of having the test done during this period, however, aren't clear.

Your health care provider might recommend that you have a biophysical profile once a week or twice a week, depending on your health condition — until you deliver.