Incidence and Clinical Risk Factors for Preeclampsia and Its Subtypes: A Population-Based Study in Beijing, China

Objective: This study aimed to evaluate the incidence and associated clinical risk factors for preeclampsia (PE) and its subtypes in a large multicentre retrospective study of Beijing, China. Methods: This study was conducted as a secondary analysis from the Gestational diabetes mellitus Prevalence Survey (GPS), a multicentre retrospective cohort study, which included 15 hospitals in Beijing, China. This analysis included 15,003 pregnant women who delivered in Beijing from June 20th to November 30th, 2013. The incidence of PE was calculated. Risk factors for PE, including maternal age, pre-gestational body mass index (BMI), parity, chronic hypertension, pre-existing diabetes, and gestational diabetes mellitus, were assessed. PE was defined as early- or late-onset PE based on clinical manifestations during the week of delivery, and mild or severe PE based on the severity of the disease. Logistic regression analysis was used to quantify the association with the risk factors, and data were displayed as odds risks (OR) and 95% confidence interval (CI). Results: The overall incidence of PE was 2.65% (397/15,003). The prevalence of early-onset and late-onset PE was 0.36% (54/15,003) and 2.29% (343/15,003), respectively. The prevalence of mild and severe PE was 0.91% (137/15,003) and 1.73% (260/15,003), respectively. Risk factors including high BMI considered overweight (adjusted odds risk (aOR): 1.48; 95% CI: 1.06-2.05; P = 0.02) and obesity (aOR: 2.15; 95% CI: 1.50-3.08; P < 0.001), nulliparity (aOR: 1.73; 95% CI: 1.32-2.25; P < 0.001), multiple gestation (aOR: 4.58; 95% CI: 2.86-7.32; P < 0.001), and chronic hypertension (aOR: 34.95; 95% CI: 26.60-45.93; P < 0.001), were associated with increased risk for PE. Only chronic hypertension (aOR: 13.75; 95% CI: 4.78-39.58; P < 0.001) was a significant risk factors for early-onset PE, whereas high BMI considered both overweight (aOR: 1.54; 95% CI: 1.09-2.18; P = 0.01) and obesity (aOR: 2.23; 95% CI: 1.53-3.27; P < 0.001), nulliparity (aOR: 2.00; 95% CI: 1.49-2.68; P < 0.001), multiple gestation (aOR: 4.11; 95% CI: 2.40-7.05; P < 0.001), and chronic hypertension (aOR: 35.57; 95% CI: 26.66-47.47; P < 0.001) were more relevant risk factors for late-onset PE. Risk factors including obesity (aOR: 2.20; 95% CI: 1.28-3.76; P OR: 1.80; 95% CI: 1.16-2.80; P = 0.01), nulliparity (aOR: 2.28; 95% CI: 1.44-3.60; P OR: 1.48; 95% CI: 1.09-2.02; P = 0.01), multiple gestation (aOR: 5.50; 95% CI: 2.87-10.67; P OR: 3.51; 95% CI: 1.93-6.41; P < 0.001), and chronic hypertension (aOR: 33.98; 95% CI: 22.20-52.01; P OR: 35.03; 95% CI: 25.40-48.31; P < 0.001) were associated with mild and severe PE. Moreover, we found that women with an increasing number of these risk factors had a higher risk of developing PE than pregnant women without any identified risk factors. Conclusion: The incidence of PE in this study is consistent with previous reported studies. Our findings indicate chronic hypertension and multiple gestation are the most important risk factors for PE in Chinese pregnant women. The risk for developing PE is associated with both the type and abundance of risk factors. These factors are valuable when monitoring patients at risk for PE, as this can help ensure an earlier diagnosis and prediction in women who are more likely to develop PE.