Table 3.

Estimated ORs with 95% CIs of the risk of SGA for each IQR of air pollutants during each pregnancy period compared with the reference group (lowest quartile)

Pollutant	IQRa	Entire pregnancy		Trimester 1		Trimester 2		Trimester 3
		ORb (95% CI)	P	OR (95% CI)	P	OR (95% CI)	P	OR (95% CI)	P
PM10	Q1	–		–		–		–
	Q2	3.210 (2.124–4.852)	< 0.001	0.858 (0.639–1.152)	0.308	1.012 (0.710–1.443)	0.946	1.375 (0.736–2.019)	0.104
	Q3	3.241 (2.144–4.899)	< 0.001	0.521 (0.373–0.727)	< 0.001	1.224 (0.873–1.716)	0.242	1.942 (1.353–2.786)	< 0.001
	Q4	3.038 (2.004–4.604)	< 0.001	0.475 (0.338–0.667)	< 0.001	1.590 (1.148–2.202)	0.005	2.461 (1.732–3.498)	< 0.001
PM2.5	Q1	–		–		–		–
	Q2	3.167 (2.094–4.789)	< 0.001	0.853 (0.635–1.147)	0.293	1.240 (0.868–1.773)	0.237	1.563 (1.078–2.266)	0.018
	Q3	3.159 (2.088–4.780)	< 0.001	0.570 (0.410–0.793)	0.001	1.398 (0.987–1.980)	0.059	1.665 (1.154–2.401)	0.006
	Q4	3.151 (2.083–4.768)	< 0.001	0.475 (0.337_0.670)	< 0.001	1.772 (1.267–2.478)	0.001	2.385 (1.681–3.384)	< 0.001
NO2	Q1	–		–		–		–
	Q2	0.678 (0.483–0.951)	0.024	0.789 (0.587–1.061)	0.116	0.666 (0.464–0.955)	0.027	1.993 (1.369–2.903)	< 0.001
	Q3	0.786 (0.569–1.085)	0.143	0.452 (0.321–0.637)	< 0.001	0.855 (0.612–1.194)	0.358	2.052 (1.412–2.981)	< 0.001
	Q4	0.936 (0.686–1.277)	0.678	0.504 (0.363–0.700)	< 0.001	1.454 (1.072–1.972)	0.016	2.375 (1.646–3.426)	< 0.001
SO2	Q1	–		–		–		–
	Q2	0.997 (0.711–1.397)	0.984	0.889 (0.669–1.181)	0.418	1.277 (0.917–1.779)	0.148	1.587 (1.046–2.410)	0.030
	Q3	1.046 (0.752–1.455)	0.790	0.417 (0.297–0.586)	< 0.001	1.022 (0.723–1.445)	0.902	3.138 (2.140–4.063)	< 0.001
	Q4	1.135 (0.822–1.568)	0.442	0.339 (0.235–0.490)	< 0.001	1.309 (0.942–1.819)	0.109	3.074 (2.093–4.515)	< 0.001

^aQ1: The first quartile; Q2: The second quartile; Q3: The third quartile; Q4: The fourth quartile

^bAdjusted for maternal age, parity, gestational hypertension, gestational diabetes mellitus, delivery mode, and infant sex