PM2.5 and Its Components and Hospitalization for Hypertensive Disorders of Pregnancy in Henan Province, China, 2015-2021: A Case-Crossover Study.

INTRODUCTION

The short-term effects of exposure to fine particulate matter (PM2.5) and its five components (sulfate, nitrate, ammonium salt, organic matter, and black carbon) on hospitalizations for hypertensive disorders of pregnancy (HDP) remain unclear.

METHODS

This study enrolled mothers with HDP from January 1, 2015, to December 31, 2021, in 5 cities in Henan Province, China. Daily data on PM2.5 were obtained from the Tracking Air Pollution in China, an online public dataset. The time-stratified case-crossover method was usd to assess the short-term single-day (lag0-1) and multi-day (lag01-07) lag effects of PM2.5 and its components on hospitalizations for HDP and further explored the modification effects of maternal age (<35 years and ≥35 years), season (cold and warm seasons), and the Three-Year Action Plan to Win the Blue Sky Defense War (before and after June 27, 2018) on the short-term effects.

RESULTS

A total of 8,007 mothers with HDP were enrolled. An IQR increased in exposure to PM2.5, organic matter, and black carbon, was associated with 5.7% (RR=1.057; 95% CI=1.002, 1.112) (lag01), 6.4% (1.064; 1.003, 1.126) (lag01), and 6.8% (1.068; 1.001, 1.135) (lag05) increases in the risk of HDP, respectively (all p<0.05). The effects of exposure to PM2.5 and its components were stronger in mothers aged ≥35 years, in the cold season, and in the period before the Action Plan was implemented (pmodification<0.05).

CONCLUSIONS

Short-term exposure to PM2.5 and its components was positively associated with hospitalization for HDP, particularly among mothers aged ≥35 years, during the cold season and before the implementation of the Action Plan.