Inhibition of premature labor: a multicenter comparison of ritodrine and ethanol.

A randomized controlled study was carried out at three medical centers to compare the efficacy and side effects of ethanol and ritodrine in the treatment of threatened premature labor. One hundred and thirty-five patients judged to be between the twentieth and thirty-sixth week of gestation and presenting with clinical symptoms of premature labor were included. Sixty-seven patients were treated with intravenous infusion of 10 per cent ethanol. Sixty-eight patients were treated with intravenous infusion of ritodrine for 12 hours followed by oral ritodrine. If labor recurred prematurely, up to two additional courses of ethanol or ritodrine were given. Delivery was postponed for more than 72 hours in 49 of 67 patients (73 per cent) with ethanol and in 61 of 68 patients (90 per cent) with ritodrine; this difference was significant. Patients in the ethanol group gained a mean of 27.6 days while patients in the ritodrine group gained a mean of 44.0 days. Fifty-four per cent of the ethanol group and 72 per cent of the ritodrine group carried their infants to 36 weeks of gestation. Five infants in the ethanol group and one infant in the ritodrine group died from respiratory distress syndrome. The most frequent side effect of ethanol were nausea and vomiting. The most frequent side effects of ritodrine were tachycardia and blood pressure changes which were easily controlled by lowering the infusion rate. Ethanol and ritodrine were both found to be effective inhibitors of premature labor with ritodrine giving the most favorable results.