Does antenatal corticosteroid therapy affect birth weight and head circumference?

To determine whether antenatal corticosteroid use is associated with weight and head circumference at birth.

We conducted a retrospective analysis of nonanomalous newborns admitted to 100 neonatal intensive care units from 23 to 34 6/7 weeks of gestation using multivariable analysis of variance that controlled for several potentially confounding variables.

There were 14,338 cases of birth weight and 13,670 for head circumference available for analysis. Independent variables included maternal age, race, nulliparity, poor prenatal care, multiple gestation, obstetric complications, alcohol, smoking, illicit drugs, presentation, gestational age at birth, and method of delivery. The mean (+/-SD) birth weight was 1671 +/- 574 g and head circumference was 289 +/- 33 mm. The multivariable effect of antenatal corticosteroid on birth weight (mean +/- SE) was -63 +/- 5.7 g and on head circumference was -3.1 +/- 0.4 mm. Even after controlling for birth weight, a significant reduction in head circumference (-1.2 +/- 0.3 mm; 95% CI = -1.8, -0.6) was associated with antenatal corticosteroid use. This suggested that antenatal corticosteroids were associated with a greater reduction in brain growth than somatic growth.

Antenatal corticosteroid may be associated with a reduction in birth weight and head circumference, independent of other major predictive factors. The reduction in head circumference persists even after controlling for the reduction in birth weight. The clinical significance of these findings is unknown.