[Association between gestational weight gain and pre-eclampsia stratified by pre-pregnancy body mass index]

Objective: To investigate the effect of gestational weight gain (GWG) on the incidence of pre-eclampsia (PE) and to establish an ideal GWG range for preventing PE based on pre-pregnancy body mass index (BMI) stratification. Methods: The clinical data of 87 109 singleton pregnant women who delivered in Women's Hospital, Zhejiang University School of Medicine from January 2017 to December 2022 were retrospectively analyzed. Pregnant women were divided into PE group (n=2 900) and non-PE group (n=84 209) according to the presence or absence of PE. Pregnant women with severe PE (sPE) in the PE group were divided into sPE subgroup (n=1 376). Pregnant women were stratified into three groups according to their pre-pregnancy BMI: non-overweight/obesity, overweight and obesity. Multivariate logistic regression was used to analyze the effect of pre-pregnancy BMI on PE. Restricted cubic spline (RCS) model was used to fit the dose-response curve, and the relationship between the deviation of GWG from the recommended midpoint of the "Recommendations for Gestational Weight Gain in Pregnant Women (WS/T 801-2022)" and the incidence of PE was analyzed. The ideal GWG range for preventing PE in each pre-pregnancy BMI stratification was also inferred. Results: (1) In the non-PE group, the proportions of non-overweight/obesity, overweight and obesity were 87.07% (73 322/84 209), 11.18% (9 412/84 209) and 1.75% (1 475/84 209), respectively. In the PE group, the non-overweight/obesity, overweight and obesity accounted for 63.14% (1 831/2 900), 26.10% (757/2 900) and 10.76% (312/2 900), respectively. In the sPE subgroup, non-overweight/obesity, overweight and obesity accounted for 65.77% (905/1 376), 24.13% (332/1 376) and 10.10% (139/1 376), respectively. Compared with the non-PE group, the PE group and the sPE subgroup had a significantly higher proportion of pre-pregnancy overweight and obesity (all P<0.001). (2) After adjusting for covariates, the risk of PE in both overweight (aOR=2.49, 95%CI: 2.25-2.76) and obesity (aOR=5.57, 95%CI: 4.80-6.47) group was significantly higher than that in non-overweight/obesity group (all P<0.001). (3) RCS curve analysis showed that the risk of PE in pregnant women with different pre-pregnancy BMI levels increased in a dose-dependent manner with the deviation value of GWG. (4) The optimal GWG for PE prevention was generally located in the lower part of the recommended range of WS/T 801-2022 standard. The suggested GWG for non-overweight and obese pregnant women, overweight and obese pregnant women were 8.6-12.5 kg, 4.0-7.5 kg and 3.0-4.3 kg, respectively. Conclusion: Pre-pregnancy overweight or obesity significantly increased the risk of PE. It is suggested that the ideal GWG range for PE prevention should be controlled at the lower end of the recommended range of WS/T 801-2022 standard. Women who are overweight or obese before pregnancy should adopt more conservative weight management strategies to reduce the risk of PE.