Antepartum fetal evaluation: development of a fetal biophysical profile

Five fetal biophysical variables, fetal breathing movements, fetal movements, fetal tone, qualitative amniotic fluid volume, and the nonstress test, were measured in the same observation period in 216 patients with high-risk pregnancies. All delivered within one week of the last observation. The relationship between individual biophysical variables and combinations of variables to the outcome of pregnancy as judged by five-minute Apgar score, fetal distress in labor, and perinatal mortality rate (PMN) was determined. For any single test, the false negative rate was low and was similar between tests, but the false positive rate was high (greater than 50%) and varied significantly between tests. Combining tests resulted in a significant change in both the false negative and false positive rates as compared to any single test. The most accurate differentiation of the normal from the compromised fetus was obtained when all five variables were studied. The PNM ranged from 0 when all variables were normal to 600 per 1,000 when all were abnormal. These data suggest that combined fetal biophysical testing is a more accurate method of antepartum fetal evaluation than any single method.