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 examined the correlation between antenatal corticosteroid therapy (ACT) exposure and birth size—birth weight (BWT), birth length (BL), ponderal index (PI), and head circumference (HC). During the 5-year study period, a total of 278,508 live-born singleton births with ≥24 gestational completed weeks were recorded in the FMBR. Unadjusted and adjusted regression analyses, as well as propensity score matching (PSM), were used to analyze whether birth size differed by ACT exposure. The results obtained from this observational register-based study indicate that ACT was consistently linked to the reduction in birth size for infants born preterm, near term, or at term. Birth size deficits in relation to ACT were greatest for preterm born infants irrespective of analytical strategy.