In a study of 101 patients at term, the maternal and umbilical cord artery and vein levels of human placental lactogen (hPL) were correlated against the sex and birthweight of the fetus. No difference in hPL levels was found between cord artery and vein. The maternal hPL level correlated well with the delivered weight of the child, but no relationship could be demonstrated in the case of umbilical cord blood. Pregnancies with a female child had a higher level of hPL, which was significant only in cord samples.