EVIDENCE SUMMARY
A 2016 systematic review and meta-analysis of 3 RCTs that included 3200 women with late preterm labor (between 34 weeks 0 days and 36 weeks 6 days) found that women who were given betamethasone had a significantly lower incidence of transient tachypnea of the newborn (number needed to treat [NNT]=37; relative risk [RR]=0.72; 95% confidence interval [CI], 0.56-0.92), severe respiratory distress syndrome (NNT=114; RR=0.60; 95% CI, 0.33-0.94), and use of surfactant (NNT=92; RR=0.61; 95% CI, 0.38-0.99).1
A composite outcome measure also favors betamethasone
In addition to these 3 outcomes, the largest RCT in the meta-analysis evaluated a composite outcome and found that betamethasone improved it by 20%. The RCT, comparing 1427 women in the experimental arm with 1400 controls, found benefit to administering 12 mg betamethasone intramuscularly every 24 hours for 2 days for women at high risk of late preterm delivery.2 Enrollment criteria included women with 3 cm dilation or 75% effacement, preterm premature rupture of membranes, or a planned delivery scheduled in the late preterm period.
The primary outcome was a composite score based on one or more of the following within 72 hours after birth: continuous positive airway pressure or high-flow nasal cannula for at least 2 continuous hours, supplemental oxygen with a fraction of inspired oxygen of 0.30 or more for at least 4 continuous hours, mechanical ventilation, stillbirth or neonatal death, or the need for extracorporeal circulation membrane oxygenation. The betamethasone group had 165 women (11.6%) with the primary outcome compared with 202 (14.4%) in the control arm (NNT=34; RR=0.80; 95% CI, 0.66–0.97; P<.02).
Neonatal hypoglycemia may increase, but not dangerously
The same RCT explored the risks of late preterm betamethasone. There was no increase in chorioamnionitis nor neonatal sepsis in the betamethasone group.2 Although neonatal hypoglycemia increased (24% vs 15%; number needed to harm=11.1; RR=1.60; 95% CI, 1.37-1.87; P<.001), no increase was seen in intermediate care nursery or ICU stays (41.8% vs 44.9%; RR=0.93; 95% CI, 0.85-1.01; P=.09) nor length of hospital stay (7 vs 8 days; P=.20).
Three letters to the editor questioned whether hypoglycemia from late-term corticosteroids may lead to long-term neurocognitive delays.3 The authors responded that meta-analyses of RCTs haven’t found an association between antenatal steroid use and neurocognitive delay and that studies that have found an association between hypoglycemia and neurocognitive delay looked at profound and prolonged hypoglycemia, which wasn’t seen in the late preterm betamethasone study.
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