Antenatal dexamethasone and decreased birth weight.

OBJECTIVE

To test the hypothesis that antenatal dexamethasone treatment to promote fetal lung maturation results in decreased birth weight corrected for gestational age.

METHODS

The birth weights of all dexamethasone-treated, singleton, live-born infants delivered at our hospital were compared with our overall obstetric population; a group of untreated infants frequency matched approximately 3:1 according to maternal race, infant sex, and gestational age at delivery; and an historical cohort of infants with an indication for dexamethasone but delivered in the 12 months before the introduction of corticosteroid therapy at our hospital.

RESULTS

Dexamethasone-treated infants (n = 961), when compared with either the overall population (n = 122,629) or matched controls (n = 2808), had significantly lower birth weights after adjustment for week of gestation (P <.001). Compared with the historical cohort of infants, the average birth weight of dexamethasone-treated infants was smaller by 12 g at 24-26 weeks, 63 g at 27-29 weeks, 161 g at 30-32 weeks, and 80 g at 33-34 weeks' gestation.

CONCLUSION

Antenatal dexamethasone administered to promote fetal maturation is associated with diminished birth weight.