Table 2.

Chronic associations between extreme ambient temperatures and stillbirth among singleton births in the consortium on safe labor, 2002–2008 (cohort analysis).

Exposure windows	Unadjusted		Adjusteda		Adjustedb
	OR	95% CI	OR	95% CI	OR	95% CI
	Hot
Preconception	0.91	0.73, 1.13	0.98	0.77, 1.24	1.02	0.80, 1.30
Trimester 1	0.73	0.58, 0.93	0.83	0.64, 1.07	0.83	0.63, 1.08
Trimester 2c	1.13	0.89, 1.44	1.06	0.82, 1.37	1.03	0.78, 1.34
Whole Pregnancy	3.79	3.24, 4.42	3.80	3.16, 4.56	3.71	3.07, 4.47
Cold
Preconception	1.25	1.03, 1.51	1.23	0.99, 1.53	1.21	0.97, 1.50
Trimester 1	0.94	0.76, 1.16	0.92	0.72, 1.17	0.91	0.71, 1.16
Trimester 2c	0.83	0.63, 1.09	0.90	0.67, 1.20	0.90	0.68, 1.22
Whole Pregnancy	3.93	3.37, 4.58	4.54	3.78, 5.45	4.75	3.95, 5.71

Note: Bold face indicates statistical significance at $p<0.05$. CI, confidence interval; OR, odds ratio.

^aAdjusted for clustering resulting from multiple singleton deliveries for the same mother and potential confounders including study site, infant sex, maternal age, race, marital status, parity, prepregnancy BMI, hypertensive disorders of pregnancy, insurance status, humidity, and season of conception.

^bAdditionally adjusted for exposures to particulate matter with diameter $<2.5\mathrm{\mu }\mathrm{m}$ and ozone.

^cAnalyses were based on pregnancies with a completed second trimester (664 stillbirths and 220,345 live births).