Correlation between exposure to fine particulate matter and hypertensive disorders of pregnancy in Shanghai, China

Background Association between fine particulate matter (PM2.5) and hypertensive disorders of pregnancy (HDP) is inconsistent and appears to change in each trimester. We aim to investigate the association of exposure to ambient PM(2.5)in early pregnancy with HDP. Methods A retrospective cohort study was performed among 8776 women with singleton pregnancy who attended the antenatal clinic before 20 gestational weeks in a tertiary women's hospital during 2014-2015. Land use regression models were used to predict individual levels of PM(2.5)exposure. Results The average PM(2.5)concentration during the first 20 gestational weeks ranged from 28.6 to 74.8 mu g m(- 3)[median, 51.4 mu g m(- 3); interquartile range, 47.3-57.8 mu g m(- 3)]. A total of 440 (5.0%) women was diagnosed with HDP. The restricted cubic spline showed a positive exposure-response relationship between the PM(2.5)concentration and risk of HDP. We observed an association between PM(2.5)exposure during the first trimester with HDP (RR = 3.89 per 10 mu g m(- 3), 95% CI: 1.45-10.43), but not during the second trimester (RR = 0.71 per 10 mu g m(- 3), 95% CI: 0.40-1.27). Compared with their counterparts, nulliparous women who were exposed to high levels of PM(2.5)in the index pregnancy had a higher risk of developing HDP [the relative excess risk due to interaction was 0.92 (0.46-1.38)]. Conclusion Our findings suggest that PM(2.5)exposure during the first trimester is associated with the development of HDP. The effect estimate is more obvious for nulliparous women than multiparous women.