Low-dose ethanol for inhibition of preterm uterine activity.

Inhibition of preterm labor by tocolytic agents reduces the incidence of preterm birth. Betamimetic drugs are the most widely used tocolytic. However, they are from time to time contraindicated, their administration involves potential risks for mother and fetus, and their tocolytic effect is sometimes insufficient. Ethanol infused in intoxicating doses was the first clinically useful tocolytic agent, but because of its potential risks to the fetus, its use is now infrequent. We have examined the efficacy of ethanol infused at much lower rates, alone or in combination with ritodrine, to inhibit preterm uterine contractions. Fifty-four women between 20 and 36 weeks of gestation participated in the study. In 14, betamimetics were contraindicated and they were given ethanol alone. In 38, ritodrine infusions (0.2 gm/min) had failed to arrest preterm labor and they were then given ethanol with ritodrine (0.2 gm/min) The dose of ethanol was 0.11 gm/kg/hour on the average, which is approximately equivalent to the metabolic rate. Altogether, 64 treatments were given, 14 with ethanol alone and 50 combined with 0.2 gm/min ritodrine. In 81% of the treatments, contractions were suppressed within 15.3 hours on the average. Preterm birth (infant less than 2500 gm) was prevented in 70% of the patients. No adverse effects attributable to ethanol were observed. Treatment with low-dose intravenous infusion of ethanol is a cheap, efficacious, and low-risk method to stop preterm uterine activity and is clinically useful for prevention of preterm birth. Possible mechanism of this effect is discussed.