Sex-specific associations of maternal prenatal testosterone levels with birth weight and weight gain in infancy.

Associations between maternal salivary testosterone at 36 weeks' gestation with birth weight and infant weight gain through 6 months of age were examined in a group of 49 healthy, pregnant women and their offspring. The diurnal decline of maternal testosterone was conserved in late pregnancy, and levels showed significant day-to-day stability. Elevated maternal morning testosterone level was associated with lower birth weight Z-scores adjusted for gestational age and sex, and greater infant weight gain between birth and 6 months. Although maternal testosterone levels did not differ by fetal sex, relations were sex-specific such that maternal testosterone had a significant impact on weight for male infants; among female infants associations were nonsignificant. Results highlight the opposing influence of maternal androgens during pregnancy on decreased growth in utero and accelerated postnatal weight gain.