Table 1.

Basic Characteristics of the Japan and Gunma Nurses' Health Studies

	JNHS		GNHS
Total number	15,019		698
Age at baseline
Mean (SD)	41.8	(8.2)	37.3	(10.1)
Median (Q1-Q3)	41	(35-48)	37	(28-45)
<30 years	498	(3.3%)	194	(27.8%)
30-34 years	2859	(19.0%)	96	(13.8%)
35-39 years	3061	(20.4%)	115	(16.5%)
40-44 years	3026	(20.1%)	107	(15.3%)
45-49 years	2672	(17.8%)	95	(13.6%)
50-54 years	1959	(13.0%)	53	(7.6%)
55-59 years	764	(5.1%)	33	(4.7%)
60-64 years	138	(0.9%)	5	(0.7%)
65+ years	42	(0.3%)	0	(0.0%)
Follow-up years
Mean (SD)	11.9	(4.4)	14.3	(5.3)
Median (Q1-Q3)	14	(10-16)	18	(10-18)

JNHS, Japan Nurses' Health Study; GNHS, Gunma Nurses' Health Study; SD, standard deviation; Q1, 25 percentile; Q3, 75 percentile