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Antenatal steroids are now formally recommended for women in the late preterm period who are at risk of preterm birth within 7 days, according to new statements from the (SMFM) and the (ACOG).

Betamethasone should be administered to women from 34 weeks to 37 weeks gestation who also have evidence of preterm labor, such as cervical dilation of at least 3 cm or effacement of 75%, wrote the SMFM Publications Committee in a statement to be published in the .

These new practice guidelines come on the heels of the (ALPS) trial, a large multi-center randomized trial funded by the National Institute of Child Health and Human Development (NICHD). The results of the ALPS trial were presented by , of Columbia University in New York City, and colleagues, at the SMFM annual meeting in February, and published in the .

The ALPS trial found an improvement in neonatal outcomes with betamethasone compared to placebo, including a significant reduction in respiratory complications for the infant. The betamethasone group also was associated with a lower incidence of respiratory conditions, such as bronchopulmonary dysplasia, need for resuscitation at birth, and use of surfactant.

"The rationale to implement [this] protocol into clinical practice includes its relatively large sample size, the fact that it included a study cohort generalizable to the U.S. population, and that it involved a methodologically rigorous study design and protocol that enhances its internal validity," the SMFM Publications Committee wrote.

The SMFM also recommends that pregnant women in the late preterm period with medical indications for delivery not be given betamethasone unless a late preterm delivery is planned.

ACOG released a separate, similar practice advisory endorsing the use of betamethasone for late preterm birth . They note that they are reviewing whether the protocol is appropriate for pregnant women with diabetes, multi-fetal gestations, previous exposure to steroids during pregnancy, or pregnancies with major nonlethal fetal malformations, since these conditions were excluded from the ALPS trial.

Both SMFM and ACOG advise against the use of tocolysis to delay preterm labor, even if the full course of betamethasone has not been completed. Both groups also suggest that infants whose mothers receive antenatal steroids should be monitored for hypoglycemia, as the ALPS trial did find a significant difference in neonatal hypoglycemia in the betamethasone group compared to the placebo group.

But some experts sounded a note of caution. in the NEJM by and , both of the University of Auckland in New Zealand, pointed out that neonatal hypoglycemia has been associated with developmental delay in these preterm infants.

"The trial protocol suggests that follow-up is planned up to 6 months of age, but much longer developmental follow-up will be essential to assess whether the neonatal respiratory benefits translate into later health and developmental benefits without harm, as has been shown in other trials," they wrote.

(WHO), , and the all previously recommended the use of antenatal corticosteroids for women up to 34 weeks gestation.