Table 2.

Results from logistic regression analysis of infertility in accordance with long working hours and age group

Subgroup	Odds ratio (95% confidence interval), referred to the group of non-long working hours
	Crude model	Model 1	Model 2	Model 3
Overall (n = 5,909)	1.30 (0.95–1.74)	1.27 (0.93–1.71)	1.28 (0.93–1.72)	1.18 (0.85–1.61)
Subgroup for age group
<40 y (n = 2,620)	1.96 (1.22–3.04)	1.97 (1.22–3.06)	1.97 (1.22–3.07)	1.91 (1.17–3.01)
≥40 y (n = 3,289)	0.99 (0.65–1.47)	0.99 (0.64–1.46)	0.99 (0.64–1.47)	0.87 (0.55–1.31)
Subgroup for contraceptive experience
Yes (n = 487)	3.19 (1.37–8.71)	3.15 (1.23–9.22)	3.27 (1.27–9.58)	2.94 (1.12–8.76)
No (n = 5,422)	1.09 (0.71–1.61)	1.07 (0.69–1.58)	1.07 (0.70–1.58)	0.97 (0.62–1.47)
Subgroup for abortion experience
Yes (n = 1,791)	0.77 (0.43–1.30)	0.81 (0.45–1.36)	0.81 (0.45–1.37)	0.68 (0.37–1.19)
No (n = 4,118)	1.67 (1.15–2.37)	1.62 (1.11–2.29)	1.62 (1.11–2.30)	1.55 (1.05–2.24)

Model 1: adjusting for age.

Model 2: Model 1 + adjusting for education and average monthly household income.

Model 3: Model 2 + adjusting for occupational classification and employment type.