Association of induced abortion with hypertensive disorders of pregnancy risk among nulliparous women in China: a prospective cohort study

The relationship between induced abortion(IA) and hypertensive disorders of pregnancy(HDP) is inconclusive. Few studies have been conducted in China. In order to clarify the association between previous IA and risk of HDP, including gestational hypertension(GH) and pre-eclampsia(PE), we performed a community-based prospective cohort study enrolling 5191 eligible nulliparous women in selected 2 districts and 11 towns of Liuyang from 2013 to 2015. Multivariable logistic regression was conducted to examine whether IA was associated with HDP, GH and PE. Of the gravidea, 1378(26.5%) had a previous IA and 258(5.0%) diagnosed with HDP, including 141(2.7%) GH and 117(2.3%) PE. The difference in the incidence of GH and PE between gravidae having one versus those with two or more IAs was minimal. After adjustment for maternal age, body mass index at first antenatal visit, education, virus infection and history of medical disorders, previous IA was significantly associated with HDP (OR = 0.67, 95%CI = 0.49 to 0.91) and PE (OR = 0.61, 95%CI = 0.38 to 0.97), but not with GH (OR = 0.73, 95%CI = 0.49 to 1.10). Additional adjustment for occupation, living area, anemia, gestational diabetes mellitus, psychological stress, conception climate and infant sex, multivariable analysis provided similar results. In conclusion, previous IA was associated with a lower risk of PE among nulliparous women.