Rodriguez A, et al. - Using data from the Finnish Medical Birth Register (FMBR) covering all births in Finland (January 1, 2006–December 31, 2010), researchers conducted this observational register-based study to examine whether birth size differed by antenatal corticosteroid therapy (ACT) exposure and to evaluate differences in birth size in treated vs untreated pregnancies. In this population cohort study of 278,508 live-born singleton births, ACT has consistently been associated with a reduction in birth size for preterm, near term or term-born infants. Regardless of the analytic strategy, deficits in birth size in relation to ACT were greatest for infants born preterm.