Antepartum fetal heart rate monitoring: value of sound stimulation.

The fetal heart rate (FHR) response to sound stimulation has been studied. The normal fetus exhibits an acceleration of at least 15 beats/min sustained for at least 2 minutes. This response was studied in 116 pregnancies in which the fetus was considered to be at high risk. The response was impaired in the 3 cases of perinatal death, in 14 of 19 cases of perinatal morbidity, and in 17 of 27 fetuses whose subsequent birth weight was below the fifth percentile. An impaired response was of greater predictive value than the nonreactive pattern of nonstressed FHR monitoring.