Figure 2 A stratified sub-analysis of associations between air pollutants throughout the pregnancy and PROM stratified by pressure and systolic pre-pregnancy BMI categories (kg/m2). Underweight is defined as pre-pregnancy BMI <18.5, normal weight as 18.5≤ pre-pregnancy BMI <24., overweight as 24.0≤ pre-pregnancy BMI <28.0, and obese as pre-pregnancy BMI ≥28.0. The P value represents the comparison between BMI subgroups, determined through Cochran’s Q test. Models were adjusted for age, pre-pregnancy BMI, premature birth, diastolic blood pressure, systolic blood pressure, family history of diabetes, parity, season of delivery, and temperature. The authors utilized GraphPad Prism 7.0 (GraphPad Software, Inc.) to generate all figures.