A prospective, randomized trial of nifedipine vs. ritodrine in threatened preterm labor.

OBJECTIVES

To compare the tocolytic efficacy and maternal tolerance of nifedipine with ritodrine in the management of threatened preterm labor.

METHODS

Prospective randomized study of 52 singleton pregnancies with preterm labor between 26 and 34 week's gestation. The capacity to delay delivery 48 h, 7 days, until week 36 or until fetal weight reached 2500 g were the outcome variables assessed. Doppler ultrasound studies were performed on the fetal umbilical artery as control.

RESULTS

No significant differences were found in the delay of delivery, but significantly fewer maternal side-effects were found in the nifedipine group. Doppler ultrasound results were similar in both groups.

CONCLUSIONS

Nifedipine is a valid and well-tolerated alternative among the tocolytic drugs, and apparently does not significantly alter fetal vascular blood flow.