Increased maternal serum hCG concentrations in the presence of a female fetus as early as 2 weeks after IVF-ET.

BACKGROUND

Maternal serum human chorionic gonadotropin (hCG) is produced in trophoblast cells during pregnancy. Whether there are sex-related growth differences of hCG concentrations in early pregnancy is still controversial.

OBJECTIVE

To explore the association between hCG concentrations and fetal sex as early as 2 weeks after in vitro fertilization and embryo transfer (IVF-ET).

METHODS

This study involved 6669 women ≤ 38 years of age. These 6669 patients all delivered singletons; 3531 had a male fetus and 3138 had a female fetus. The maternal serum hCG concentrations on Day 14 and Day 21 were determined using a Beckman DxI800 immunoassay system.

RESULTS

Among the 6669 patients who delivered singletons, 3531 had a male fetus and 3138 had a female fetus. The hCG concentrations on day 14 of gestation were 516.12 (342.12-757.34) IU/L in the group of male fetuses and 552.69 (359.35-772.83) IU/L in group of female fetuses. The hCG concentration on day 21 was 8839.60 (5975.00-12615.00) IU/L in male fetuses and 9289.10 (6162.00-13146.00) IU/L in female fetuses. Maternal serum hCG levels were significantly higher in those with female fetuses than those with male fetuses. After adjusting for confounding factors, the hCG levels were significantly associated with fetal sex.

CONCLUSIONS

Our results showed pregnant women with female fetuses have significantly higher hCG levels than those bearing male fetuses.