Maternal adiposity as an independent risk factor for pre‐eclampsia: a meta‐analysis of prospective cohort studies

Studies investigating the association between maternal adiposity and risk of pre‐eclampsia showed contradictory results. Therefore, we performed a meta‐analysis of prospective cohort studies to estimate the effect of maternal adiposity on pre‐eclampsia. We reviewed 1,286 abstracts and finally included 29 prospective cohort studies with 1,980,761 participants and 67,075 pre‐eclampsia events. We pooled data with a random‐effects model, and obtained risk estimates for five predetermined bodyweight groups: low, normal‐weight (reference), overweight, obese and severely obese. In the cohort studies that unadjusted for pre‐eclampsia risk factors, the pooled unadjusted relative risks (RR) with 95% confidence intervals (95%CI) for pre‐eclampsia of overweight, obese and severely obese women were 1.58 (95% CI 1.44–1.72, P < 0.001), 2.68 (95% CI 2.39–3.01, P < 0.001) and 3.12 (95% CI 2.24–4.36, P < 0.001), respectively. In those cohorts that adjusted for pre‐eclampsia risk factors, the pooled unadjusted RRs for pre‐eclampsia of overweight, obese and severely obese women were 1.70 (95% CI 1.60–1.81, P < 0.001), 2.93 (95% CI 2.58–3.33, P < 0.001) and 4.14 (95% CI 3.61–4.75, P < 0.001), respectively. Sensitivity analysis showed maternal adiposity was associated with increased risk of pre‐eclampsia in both nulliparous and multiparas women. In conclusion, overweight or obese pregnant women have a substantially increased risk of pre‐eclampsia, and maternal adiposity is an independent risk factor of pre‐eclampsia.