Human chorionic gonadotropin and risk of pre-eclampsia: prospective population-based cohort study

OBJECTIVES: Abnormal placentation in early pregnancy may play a role in the pathogenesis of pre-eclampsia. Human chorionic gonadotropin (hCG) regulates placental development and angiogenesis and may affect the ratio of soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) in the serum. The aims of this study were to investigate the association of total hCG with the risk of pre-eclampsia and to examine the potential effect of pro- and anti-angiogenic factors on this association. METHODS: This was a population-based prospective cohort study of 7754 women with a singleton pregnancy. Total hCG was measured in the first available sample (median gestational age, 14.4 weeks; 95% range, 10.1-26.1 weeks) and sFlt-1 and PlGF concentrations in early (< 18 weeks; median, 13.2 weeks; 95% range, 9.6-17.6 weeks) and in mid- (18-25 weeks; median, 20.4 weeks; 95% range, 18.5-23.5 weeks) pregnancy. We tested the association of hCG concentration and risk of pre-eclampsia using regression analysis, adjusting for maternal age, ethnicity, body mass index, parity, education level, smoking status and fetal sex. Additionally, we assessed whether this association was affected by the sFlt-1/PlGF ratio. RESULTS: High hCG concentration was associated with a 1.5-2.7-fold increased risk of pre-eclampsia (P = 0.0001), depending on the cut-off used, and with increased sFlt-1/PlGF ratio during early pregnancy (P < 0.0001). The association between high hCG and pre-eclampsia attenuated by roughly 40% after adjustment for early-pregnancy sFlt-1/PlGF ratio (β-estimate change from 0.19 ± 0.10 (P = 0.052) to 0.12 ± 0.10 (P = 0.22)). CONCLUSIONS: High total hCG concentration in early pregnancy is associated with an increased risk of pre-eclampsia. The effect of high hCG concentration on the balance between pro- and anti-angiogenic factors during pregnancy may have a role in the pathophysiology of pre-eclampsia.

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