Table 3.

Preterm birth (all pregnancies, n = 79,328) and low birth weight (< 2,500 g) and birth weight (g) among term births (n = 72,920) in association with PM₁₀ during each trimester.

Exposure	Preterm birth [OR (95% CI)]	Birth weight (g) [coefficient (95% CI)]	LBW [OR (95% CI)]
Adjusted for maternal age, education, marital status, pregnancy conditions, maternal smoking status, and onset of prenatal care; temperature, rain, humidity, air pressure, and windspeed intensity in each trimester of pregnancy; indicators for calendar quarter of gestation; and indicators for prenatal care center. Third trimester values for PM10 and weather variables are averaged across gestation weeks 28 and 36 (or an earlier week if the pregnancy did not reach full term) when the outcome is PTB. In the case of BW or LBW, 3rd trimester averages consider the full length of the trimester until birth. **p < 0.01. *p < 0.05. #p < 0.10.
First trimester
< 30 μg/m3	Reference	Reference	Reference
30–49 μg/m3	0.92 (0.780, 1.08)	–10.03 (–26.78, 6.73)	1.05 (0.83, 1.33)
50–69 μg/m3	0.85 (0.66, 1.08)	–3.76 (–28.16, 20.64)	0.98 (0.68, 1.40)
≥ 70 μg/m3	0.690 (0.47, 1.02)#	–24.26 (–70.81, 22.29)	1.23 (0.64, 2.37)
Second trimester
< 30 μg/m3	Reference	Reference	Reference
30–49 μg/m3	0.79 (0.64, 0.97)*	16.83 (–2.49, 36.15)#	0.98 (0.74, 1.29)
50–69 μg/m3	0.76 (0.59, 0.99)*	31.28 (1.89, 60.67)*	1.14 (0.74, 1.74)
≥ 70 μg/m3	0.86 (0.58, 1.28)	103.98 (60.89, 147.06)**	0.77 (0.41, 1.45)
Third trimester
< 30 μg/m3	Reference	Reference	Reference
30–49 μg/m3	1.00 (0.85, 1.17)	–7.96 (–26.02, 10.10)	0.83 (0.63, 1.08)
50–69 μg/m3	1.42 (1.07, 1.89)*	57.55 (29.24, 85.86)**	0.52 (0.35, 0.78)**
≥ 70 μg/m3	5.24 (3.40, 8.08)**	17.89 (–24.55, 60.34)	0.78 (0.43, 1.42)
Model fit
Akaike Information Criterion (AIC)	43,741	1,094,438	17,298
Bayesian Information Criterion (BIC)	44,502	1,095,192	18,052