Table 4.

PAF associated with chronic exposure to extreme ambient temperature among singleton births in the consortium on safe labor, 2002–2008.

Whole-pregnancy temperature	PAFa	95% CI	Total cases	Excess cases	95% CI
Cold	0.19	0.18, 0.20	247	48.0	45.2, 50.2
Hot	0.17	0.16, 0.19	238	42.1	39.0, 44.6

Note: Bold face indicates statistical significance established at $p<0.05$; CI, confidence interval; PAF, population attributable fraction.

^aPAF was calculated using the following formula: $\text{PAF}=\text{pd}\left[\right(\text{OR}-1)/\text{OR}]$, expressed as a proportion.