Table 3.

Adjusted pooled odds ratios (95% confidence intervals) of spontaneous premature rupture of membranes associated with air pollution exposure during trimesters and throughout the pregnancy in the single-pollutant model.

Air pollutants	Exposure windows
	1st trimester	2nd trimester	3rd trimester	Entire pregnancy
Krigged NO2	1.05 (1.03, 1.08)	0.98 (0.95, 1.01)	1.07 (1.05, 1.09)	1.06 (1.03, 1.09)
Krigged O3	1.04 (1.02, 1.05)	1.00 (0.99, 1.02)	1.02 (1.01, 1.04)	1.07 (1.05, 1.10)
Krigged PM2.5	1.01 (0.99, 1.03)	1.04 (1.02, 1.06)	1.02 (1.01, 1.04)	1.07 (1.05, 1.09)
Krigged PM10	1.01 (1.00, 1.02)	1.00 (0.99, 1.01)	1.00 (0.99, 1.02)	1.02 (1.00, 1.04)
PM2.5 total mass	0.99 (0.97, 1.02)	1.07 (1.04, 1.09)	1.02 (1.00, 1.05)	1.09 (1.06, 1.11)
PM2.5 sulfate	1.03 (1.01, 1.05)	1.04 (1.01, 1.06)	1.04 (1.02, 1.06)	1.08 (1.05, 1.12)
PM2.5 nitrate	1.00 (0.99, 1.02)	1.04 (1.03, 1.06)	1.02 (1.00, 1.03)	1.06 (1.04, 1.08)
PM2.5 ammonium	1.01 (1.00, 1.03)	1.04 (1.03, 1.06)	1.01 (1.00, 1.03)	1.07 (1.05, 1.09)
PM2.5 organic matter	0.98 (0.96, 1.00)	1.07 (1.04, 1.10)	1.01 (0.99, 1.03)	1.06 (1.04, 1.09)
PM2.5 black carbon	1.00 (0.98, 1.03)	1.01 (0.98, 1.05)	1.01 (0.98, 1.04)	1.01 (0.98, 1.04)

Note: The exposure to four krigged air pollutants was measured based on empirical Bayesian kriging. The exposure to PM_2.5 total mass and components was measured based on a fine-resolution geoscience-derived model. IQR increments are 6.69 ppb for NO₂, 9.89 ppb for O₃, 3.26 μg/m³ for PM_2.5, 6.82 μg/m³ for PM₁₀, 3.91 μg/m³ for PM_2.5 total mass, 0.627 μg/m³ for PM_2.5 sulfate, 0.946 μg/m³ for PM_2.5 nitrate, 0.421 μg/m³ for PM_2.5 ammonium, 1.99 μg/m³ for PM_2.5 organic matter, and 1.05 μg/m³ for PM_2.5 black carbon. All models were adjusted for maternal age, race/ethnicity, education level, income level, pre-pregnancy body mass index, smoking status, parity, year of infant birth, and season of conception.