Similarities and Differences Between the Risk Factors for Gestational Hypertension and Preeclampsia: A Population Based Cohort Study in South China

Objectives: To compare the risk factors for gestational hypertension (GH) and preeclampsia (PE) in the same population, which may provide clues to better understanding of their etiologic mechanisms.

Methods: We conducted a cohort study in Liuyang, China, during 2010-2011. Twelve potential risk factors were investigated, including maternal age, body mass index at first antenatal visit, gender of newborn, parity, abortion history, smoking history, family history of hypertension, gestational diabetes mellitus, pregnancy complications of diabetes mellitus/renal disease/cardiac disease, reproductive tract infection, season of delivery, and district level average per capita income. Logistic regression were used to estimate odds ratios for potential risk factors.

Results: Of 6223 pregnancies, 1.8% was complicated by PE, and 5.4% by GH. Maternal age older than 35, body mass index above 24, and pregnancy complicated with gestational diabetes mellitus increased the risk of both PE and GH, while with different effect sizes. Primiparity and deliver in winter and spring (compared with summer delivery) were risk factors for GH only. Pregnancy complicated with diabetes mellitus/renal disease/cardiac disease was risk factor for PE only. Significantly lower risk of GH was observed for women younger than 25 or with low body mass index in the first trimester. Mothers carrying a male fetus were more likely to develop PE.

Conclusions: Risk factors for GH and PE were not exactly the same. Underling those differences might be their different etiology and mechanism. To confirm the similarities and differences been found in single study, it is important to conduct investigation in other population.