Table 3.

Cumulative heat metric and fecundability (restricted to first 3 cycles of follow-up), stratified by attempt time at enrollment, infertility history, and age

	Pregnancy attempt time at enrollment		No history of infertilityat baseline		Male age at baseline
	<3 cycles				<30 years		≥30 years
	Number of males	Adjusted FR (95% CI)a	Number of males	Adjusted FR (95% CI)a	Number of males	Adjusted FR (95% CI)a	Number of males	Adjusted FR (95% CI)a
Cumulative heat metricb
0 heat factors	464	Reference	595	Reference	225	Reference	421	Reference
1 heat factor	960	1.03 (0.92–1.16)	1265	1.00 (0.87–1.13)	488	1.14 (0.91–1.42)	896	0.90 (0.77–1.05)
2 heat factors	544	1.03 (0.90–1.18)	700	1.02 (0.88–1.18)	273	1.35 (1.05–1.74)	496	0.89 (0.74–1.07)
3 heat factors	129	1.01 (0.82–1.24)	172	0.96 (0.75–1.22)	60	1.09 (0.72–1.65)	130	0.85 (0.64–1.14)
≥4 heat factors	44	0.75 (0.51–1.11)	50	0.73 (0.48–1.13)	18	1.17 (0.62–2.22)	34	0.60 (0.34–1.04)
Cumulative heat metricc
0 heat factors	464	Reference	595	Reference	225	Reference	421	Reference
1 heat factor	897	1.00 (0.86–1.16)	1194	1.00 (0.87–1.14)	450	1.16 (0.92–1.45)	854	0.90 (0.77–1.05)
2 heat factors	424	1.05 (0.89–1.25)	535	1.01 (0.86–1.18)	205	1.35 (1.04–1.76)	378	0.90 (0.74–1.09)
3 heat factors	74	0.98 (0.71–1.36)	106	0.87 (0.65–1.18)	33	0.86 (0.50–1.50)	82	0.84 (0.59–1.19)
≥4 heat factors	21	1.09 (0.65–1.86)	26	0.95 (0.56–1.62)	9	1.42 (0.68–2.95)	18	0.76 (0.38–1.52)

^aAdjusted for age, race/ethnicity, education, total METs, alcohol intake, BMI, cigarette smoking, sleep duration, hours worked, unemployed, household income, previously fathered a child.

^b“Heat factor” defined as ≥3 saunas/month, ≥3 hot baths/month, tight fitting underwear, sitting ≥10 hours/day, fever, laptop use ≥5 hours/day, or seat heater use ≥3 hours/week.

^c“Heat factor” defined as in footnote d, but without fever. Analyses are also restricted to males without fever in the 3 months before enrollment.