Human chorionic gonadotropin, fetal sex and risk of hypertensive disorders of pregnancy: A nested case-control study.

Objectives: To assess whether human chorionic gonadotropin (HCG) and fetal sex are two independent risk factors for hypertensive pregnancy in the early second-trimester of pregnancy.

Methods: This was a retrospective nested case-control study based on a cohort of 2521 singleton pregnancies, among whom we recruited 98 hypertensive pregnancies (subdivided into severe preeclampsia, n=34; mild preeclampsia, n=29 and gestational hypertension, n=35) and 196 normotensive pregnancies. Maternal serum HCG levels were measured at 15-20 weeks of gestation and fetal sex was determined from the neonatal record. Mann-Whitney U and chi-square tests were performed to assess differences of HCG levels and fetal sex between groups. Logistic regressions were performed to evaluate the effect of HCG and fetal sex on hypertensive pregnancy.

Results: There were 35 male and 63 female fetuses in the hypertensive group, and 102 male and 94 female fetuses in the normotensive group (p=0.008). HCG (MoM) levels were significantly higher in only severe preeclamptic pregnancies (n=34) (p=0.013). There were no significant differences of the HCG (MoM) levels between male and female fetuses in each sub-group. aOR for increased maternal HCG levels and female fetus were 2.4 (95% CI: 1.434-3.954) and 2.9 (95% CI: 1.227-6.661) respectively in severe preeclamptic pregnancies compared with normotensive pregnancies.

Conclusions: There is a female preponderance in hypertensive pregnancies. Increased HCG levels and female fetus are two independent risk factors for severe preeclampsia in the early second-trimester of pregnancy.