Objective: To examine the effect of cervical ripening with prostaglandin E(2) (PGE(2)) tablets or intracervical Foley catheter on fetal breathing and body movements. Method: A randomized study of the two ripening methods was performed in 18 women at 38-42 weeks of gestation. All fetuses were normal, and patients had a Bishop score of 4 or less with intact membranes. Fetal breathing and body movements were evaluated for 30 min prior to and again 1 h after the insertion of the catheter or the application of 3 mg of PGE(2) tablets, Results: Application of PGE(2) tablets caused a decrease in the number of fetal breathing periods (20 +/- 12.6 versus 12 +/- 8, P < 0.024) and in the duration in seconds of breathing activity (537 +/- 423 versus 244 +/- 166, P < 0.027). The number and duration of fetal body movements did not change significantly. Ripening of the cervix with an intracervical Foley catheter had no significant effects on fetal breathing and body movements. Conclusion: Vaginal application of PGE(2) tablets reduced fetal breathing while the mechanical ripening of the cervix has no effect on intrauterine fetal activity.