Effect of fetal gender on maternal serum human chorionic gonadotropin levels throughout pregnancy.

Objective: Maternal serum human chorionic gonadotropin (MshCG) levels are higher in pregnant women with female fetuses than in pregnant women with male fetuses in the third trimester of pregnancy. Our aim was to examine the effect of fetal sex on MshCG levels throughout the pregnancy.

Methods: Twenty-nine uncomplicated pregnancies (14 had male fetus and 15 had female fetus) were included in the study. MshCG levels were measured four times between 8-12, 14-18, 24-28 and 32-36 weeks of pregnancy.

Results: MshCG levels were significantly higher in both sexes between 8-12 weeks than the other three measurement periods. At 8-12 and 14-18 weeks measurements, there were no sex related differences in the MshCG levels. At 24-28 (P<0.004) and 32-36 (P<0.001) weeks MshCG levels were significantly higher in pregnancies bearing female fetuses than those bearing male fetuses.

Conclusions: Fetal gender has a significant effect on MshCG levels in the third trimester of pregnancy. Accordingly, no correlation seems to exist in the first and second trimesters.