Table 1. Characteristics of 13,420 women by ABO blood type at the 2nd-year follow-up survey of the Japan Nurses’ Health Study, 2003–2009.

	ABO blood type
	O (n)	%	A (n)	%	B (n)	%	AB (n)	%	P valuea
Number of women	3,943		5,173		3,012		1,292
Birth year
Pre-1956	1,137	28.8	1,489	28.8	903	30.0	388	30.0	0.57
Post-1955	2,806	71.2	3,684	71.2	2,109	70.0	904	70.0
Smoking status
Non-smoker	3,425	86.9	4,521	87.4	2,638	87.7	1,115	86.3	0.57
Current smoker	515	13.1	651	12.6	371	12.3	177	13.7
Missing	3		1		3		0
Alcohol consumption
≤2 days/week	3,009	76.9	3,974	77.2	2,329	77.6	962	74.7	0.20
≥3 days/week	906	23.1	1,171	22.8	674	22.4	326	25.3
Missing	28		28		9		4
Rh factor
Positive	3,639	93.5	4,780	93.8	2,768	93.2	1,186	92.6	0.39
Negative	253	6.5	315	6.2	202	6.8	95	7.4
Missing	51		78		42		11
NSAID user
No	3,273	83.8	4,265	83.1	2,471	82.8	1,045	82.1	0.46
Yes	632	16.2	870	16.9	514	17.2	228	17.9
Missing	38		38		27		19
Green tea consumption
≤2 days/week	853	21.7	1,140	22.1	639	21.3	276	21.4	0.83
≥3 days/week	3,081	78.3	4,021	77.9	2,366	78.7	1,015	78.6
Missing	9		12		7		1
Coffee consumption
≤2 days/week	728	18.5	1,035	20.1	593	19.7	242	18.8	0.26
≥3 days/week	3,206	81.5	4,126	79.9	2,412	80.3	1,049	81.2
Missing	9		12		7		1
Miso soup consumption
≤3 days/week	1,961	49.9	2,535	49.1	1,471	49.0	658	51.2	0.51
≥4 days/week	1,971	50.1	2,629	50.9	1,533	51.0	628	48.8
Missing	11		9		8		6
Breakfast
Bread	1,507	41.6	1,984	41.8	1,143	41.2	450	38.0	0.13
Rice	2,116	58.4	2,767	58.2	1,631	58.8	733	62.0
Missing	320		422		238		109

NSAID, nonsteroidal anti-inflammatory drug; Rh, Rhesus.

^aChi-squared test.