Fetal sex and leptin concentrations in pregnant females

Adult females have significantly more leptin than males. We investigated the effect of fetal sex on levels of leptin and other pregnancy hormones (progesterone, estradiol, FSH, LH and beta hCG) in pregnant females during different stages of pregnancy. Serum leptin levels in pregnant females followed at King Khaled University Hospital, Riyadh, Saudi Arabia in the year 2001 were estimated at the first, second, and third trimester of pregnancy as well as after delivery. Progesterone, estradiol, FSH, LH and beta hCG levels were also measured. Leptin levels were significantly higher during all three trimesters in the pregnant females carrying female fetuses compared with those with male fetuses, while other hormones did not differ between the two groups. After delivery, the leptin levels decreased in both groups, and were still higher in the females who delivered baby girls, but the results were not statistically significant. These finding suggests that leptin might play a role in sex regulation during embryonic development.