Table 3.

Relationships between hypothyroidism during pregnancy and exposure to PM_2.5 and PM₁₀

	PM2.5		PM10
	OR (95% CI)	P	OR (95% CI)	P
250 m buffer
Pre-LMPM 90 days	0.999(0.968–1.030)	0.937	0.995(0.970–1.021)	0.716
Pre-LMPM 60 days	1.040(1.008–1.072)	0.012*	1.030(1.004–1.055)	0.021*
Pre-LMPM 30 days	1.056(1.023–1.090)	< 0.001*	1.041(1.013–1.070)	0.004*
LMPM	1.137(1.096–1.180)	< 0.001*	1.098(1.067–1.130)	< 0.001*
Post-LMPM 30 days	1.026(0.991–1.062)	0.150	1.016(0.989–1.044)	0.241
Post-LMPM 60 days	1.001(0.971–1.033)	0.930	0.998(0.973–1.023)	0.868
Post-LMPM 90 days	1.028(0.994–1.062)	0.100	1.018(0.992–1.046)	0.179
500 m buffer
Pre-LMPM 90 days	0.999(0.969–1.031)	0.966	0.996(0.971–1.021)	0.734
Pre-LMPM 60 days	1.040(1.009–1.072)	0.012*	1.030(1.005–1.056)	0.020*
Pre-LMPM 30 days	1.056(1.023–1.090)	< 0.001*	1.041(1.013–1.070)	0.004*
LMPM	1.138(1.097–1.181)	< 0.001*	1.098(1.066–1.130)	< 0.001*
Post-LMPM 30 days	1.025(0.990–1.061)	0.157	1.016(0.989–1.044)	0.254
Post-LMPM 60 days	1.001(0.970–1.033)	0.937	0.998(0.973–1.023)	0.864
Post-LMPM 90 days	1.028(0.994–1.063)	0.102	1.018(0.991–1.046)	0.181
750 m buffer
Pre-LMPM 90 days	1.000(0.969–1.031)	0.978	0.996(0.971–1.021)	0.737
Pre-LMPM 60 days	1.040(1.009–1.073)	0.011*	1.030(1.005–1.056)	0.020*
Pre-LMPM 30 days	1.056(1.023–1.090)	< 0.001*	1.041(1.013–1.070)	0.004*
LMPM	1.138(1.097–1.181)	< 0.001*	1.098(1.066–1.130)	< 0.001*
Post-LMPM 30 days	1.025(0.990–1.061)	0.165	1.016(0.988–1.044)	0.270
Post-LMPM 60 days	1.001(0.970–1.033)	0.950	0.997(0.972–1.023)	0.843
Post-LMPM 90 days	1.028(0.994–1.062)	0.108	1.018(0.991–1.045)	0.191

LMPM: last menstrual period month.; OR (95% CI): odds ratio (95% confidence interval); OR values represent the increased risk of hypothyroidism per 10 µg/m³ of ambient particulate matter exposure. *P < 0.05. All logistic regression models were adjusted for age, the season of the last menstruation, and pregnancy and delivery history