The objective of this study is to determine correlates of prolactin and growth hormone levels among pregnant women in the USA and China. We studied 304 pregnant Caucasian and 335 pregnant Chinese women. Levels of prolactin and growth hormone were measured at weeks 16 and 27 of gestation, and correlated with maternal, gestational and perinatal characteristics. Both growth hormone and, to a lesser extent, prolactin were inversely associated with pregnancy weight and body mass index, history of a previous live birth and newborn size, whereas educated women had higher levels of both hormones. Growth hormone levels were lower in women who gained more weight, smoked and had nausea and vomiting during pregnancy, whereas prolactin increased with longer total gestation. We found robust associations between maternal and newborn characteristics on the one hand and prolactin and growth hormone during pregnancy on the other.