Fetal body movements were studied for 40 minutes during the active phase of labor in 15 parturients. The total duration of fetal movements constituted 8.2% of the recording period, with a frequency of 3.8 +/- 2.1 per ten minutes. Of all the movements, 57.3% were associated with uterine contractions, while 40.7% of all uterine contractions were associated with fetal movements. All the fetuses moved in the first 30 minutes of the study period. The fetal movements that were associated with uterine contractions were longer than those not associated with contractions. Similarly, uterine contractions associated with fetal movements were longer than other uterine contractions.