SMFM Statement on Antenatal Corticosteroid Use During Late Preterm Period

The Society for Maternal-Fetal Medicine (SMFM) issued a statement on the use of antenatal corticosteroids during the late preterm birth period for women at risk of preterm birth. The statement will be published in the American Journal of Obstetrics and Gynecology.

In February, researchers with the Eunice Kennedy Shriver National Institute of Child Health and Human Development and MFMU  presented data that the use of antenatal steroids in pregnancies at risk for late preterm delivery prevents respiratory and other neonatal complications. Their study was a randomized double-blind, placebo-controlled trial that included 2,831 women with singleton pregnancies at high risk for late preterm delivery. Study patients were randomized to antenatal intramuscular (IM) betamethasone or a matching placebo. 

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The data showed women who were administered the betamethasone had a significant decrease in neonatal respiratory complications. These babies were less likely to have prolonged intensive care nursery stays, less likely to need postnatal treatment for respiratory complications, and less likely to develop bronchopulmonary dysplasia. Prior to this report, this type of treatment was only recommended in infants at risk of preterm delivery <34 weeks gestation.

Based on these findings, the SMFM recommends the following:

• In women with a singleton pregnancy between 34–36 6/7 weeks of gestation who are at high risk for preterm birth within the next seven days (but before 37 weeks of gestation), SMFM recommends treatment with betamethasone, a corticosteroid demonstrated to decrease neonatal complications in preterm infants.
• In women with preterm labor symptoms in the late preterm period, SMFM recommends waiting for evidence of true preterm labor, such as a cervical dilatation of ≥3cm or effacement of ≥75% before treatment with betamethasone.
• In women with late preterm pregnancies receiving betamethasone, SMFM recommends against the use of tocolysis in an attempt to delay delivery to complete the steroid course since it is unclear if the benefits are outweighed by the risks of attempts to delay delivery.
• In women with late preterm pregnancies with a potential medical indication for delivery, SMFM recommends betamethasone not be given unless there is a definitive plan for late preterm delivery.
• SMFM also recommends against the implementation of antenatal late preterm steroids protocol for conditions not studied in the randomized controlled trials.