Preterm birth is when a baby is born at less than 37 weeks' gestation. These babies are generally more ill and are less likely to survive than babies born at term. Preterm babies are also more likely to have some disability, and the earlier the baby is born the more likely they are to have problems. Even short-term postponement of preterm birth can improve outcomes for babies, as this gives time for the mother to be given a steroid injection to help develop the baby's lungs prior to birth. Short-term postponement of preterm birth may also give the chance to transfer the mother, if required, to somewhere where there is more expert care for the baby available.

Drugs used to try and stop labor are called tocolytics. These drugs are given to women experiencing preterm labor to try and stop or relax uterine contractions. One of the earliest drugs used to try and stop contractions was ethanol (also known as alcohol), although this is not generally used in current practice due to safety concerns for both the mother and her baby. In this review , we looked at the published studies to see if ethanol was effective in postponing labor and improving outcomes for babies, and also whether ethanol was better than other types of tocolytics used to postpone preterm labor and birth.

We searched for trials evidence on 31 May 2015 and found 12 trials total involving 1586 women, some comparing ethanol with a placebo and others comparing ethanol with other tocolytics (in this instance, all betamimetics). The trials included in this review were considered to be mostly low quality studies.

For our comparison of ethanol versus placebo control (two trials, 77 women). We found that ethanol was no better than placebo (sugar water) for any of the outcomes studied: birth <48 hours after trial entry (one trial , 35 women) or neonatal mortality (one trial , 35 women). Serious maternal adverse events and perinatal mortality was not reported. There was no differences between groups for other outcomes: preterm birth < 37 weeks or < 34 weeks, serious infant outcome , fetal alcohol syndrome/fetal alcohol spectrum disorder, or small-for-gestational age.

We also compared ethanol with other tocolytic drugs (nine trials involving 1438 women; all trials studied betamimetic drugs). We found that ethanol was worse than other betamimetic drugs at postponing birth until after 34 weeks' gestation and led to a higher rate of low birthweight babies, babies with breathing problems at birth and neonatal death (although there was no clear difference in neonatal deaths when we restricted our analyses to the better quality studies), However, we did find that, compared to betamimetics, ethanol was associated with a trend for fewer maternal side effects that required stopping or changing the drug, though this result is based on three small trials. There were no differences in other secondary outcomes of preterm birth < 37 weeks, number of days delivery was delayed, or overall maternal adverse events.

Overall, we found no evidence that ethanol was better than a placebo at postponing preterm labor and birth. Whilst there was some evidence to suggest that ethanol may be better tolerated than betamimetics, we found that ethanol was not as effective as betamimetics at postponing preterm labor and birth. None of the studies were long-term ones and thus none of them reported on the risk of giving ethanol on the babies developing fetal alcohol syndrome, which can cause mental retardation.