Table 3. Baseline profiles of fathers in the JECS Main Study and Sub-Cohort Study.

Variables	JECS Sub-Cohort Study			JECS Main Studya
	Number of valid response	n	(%)	Number of valid response	n	(%)
Number of their partner’s pregnancies	2,696			51,402
Age when their children were born, years	2,696			51,104
Total, mean (SD)		2,696	33.6 (6.0)		51,104	32.9 (5.9)
<20		2	0.1		198	0.4
20–24		122	4.5		3,173	6.2
25–29		581	21.6		11,659	22.8
30–34		857	31.8		16,867	33.0
35–39		708	26.3		12,738	24.9
≥40		426	15.8		6,469	12.7
Occupation during their partner’s early pregnancy	2,655			49,700
Administrative and managerial workers		116	4.4		2,029	4.1
Professional and engineering workers		889	33.5		15,001	30.2
Clerical workers		253	9.5		4,627	9.3
Sales workers		263	9.9		5,366	10.8
Service workers		306	11.5		5,650	11.4
Security workers		116	4.4		2,065	4.2
Agriculture, forestry and fishery workers		53	2.0		929	1.9
Manufacturing process workers		319	12.0		6,744	13.6
Transport and machine operation workers		124	4.7		2,061	4.1
Construction and mining workers		146	5.5		3,413	6.9
Carrying, cleaning, packaging, and related workers		33	1.2		828	1.7
Homemaker		4	0.2		66	0.1
Others (students, inoccupation, workers not classifiable by occupation)		33	1.2		921	1.9
Smoking habits	2,664			49,815
Never smoked		864	32.4		14,284	28.7
Ex-smokers who quit before their partner’s pregnancy		692	26.0		11,757	23.6
Smokers during their partner’s early pregnancy		1,108	41.6		23,774	47.7
Alcohol consumption	2,667			49,839
Never drank		564	21.1		10,588	21.2
Ex-drinkers		101	3.8		1,873	3.8
Drinkers		2,002	75.1		37,378	75.0
Body mass index	2,650			49,532
<18.5 kg/m2		93	3.5		1,797	3.6
18.5–24.9 kg/m2		1,822	68.8		34,204	69.1
≥25 kg/m2		735	27.7		13,531	27.3

SD, standard deviation.

^aMichikawa et al, J Epidemiol 2018;28(2):99–104 (reference No. 2).