Antenatal corticosteroids in the late preterm period for growth-restricted pregnancies

Recently, the Antenatal Late Preterm Steroids study reported that antenatal corticosteroids administered in the late preterm period (34.0-36.6 weeks' gestation) reduced the rate of neonatal respiratory complications at birth. The utility of this intervention in women with fetal growth restriction remains unclear.

This study aimed to determine whether administration of antenatal corticosteroids in the late preterm period in pregnancies with growth restriction decreased the need for respiratory support at delivery and other neonatal morbidities.

This was a single-center retrospective cohort study that included growth-restricted pregnancies delivered in the late preterm period. Growth restriction was defined as either a diagnosis of fetal growth restriction or small for gestational age by birthweight less than 10%. The primary composite outcome consisted of any 1 of the following occurring in a single neonate: requirement of continuous positive airway pressure or high-flow nasal cannula for 2 hours or more, oxygen requirement with fraction of inspired oxygen of ≥30% for 4 hours or more, mechanical ventilation at any time, stillbirth, or neonatal death. The primary outcome was compared between steroid naive pregnancies and pregnancies exposed to betamethasone in the late preterm period. Univariable and multivariable statistical analysis was performed and P<.05 was considered statistically significant.

A total of 247 women with a diagnosis of growth restriction or small for gestational age met all inclusion criteria, 111 of whom did not receive antenatal corticosteroids and 136 received late preterm antenatal corticosteroids. Demographics were similar between the groups, with the exception of those who received betamethasone being more likely to be nulliparous (P=.01) and to receive a diagnosis of preeclampsia (P=.001). The primary outcome did not differ between the 2 groups (16.2% [18/111] vs 12.5% [17/136]; P=.41). Multivariable modeling controlling for parity and preeclampsia indicated that the rate of the primary composite respiratory outcome was similar between the exposure groups (adjusted odds ratio, 0.63; P=.29). Neonatal hypoglycemia (<40 mg/dL) was more common in newborns exposed to steroids (25.2% [28 /111] vs 40.4% [55/136]; P=.012).

Administration of antenatal corticosteroids in the late preterm period for pregnancies with growth restriction did not significantly decrease the need for respiratory support in newborns at our institution. The rate of neonatal hypoglycemia increased after exposure to antenatal corticosteroids. This special population may not benefit from late preterm steroids.