Table 1.

Characteristics of the study population

Characteristics	Total	Hokkaido	Miyagi	Kyoto	Kochi	Okinawa	p valuea
Age (mean ± SD)	49.2 ± 10.1	49.4 ± 10.7	50.1 ± 10.7	48.9 ± 9.4	49.3 ± 10.1	48.5 ± 9.9	0.8
Number of delivery (mean ± SD)	1.9 ± 1	1.7 ± 0.9	2.0 ± 0.9	1.8 ± 0.9	1.9 ± 0.9	2.0 ± 1.4	0.3
Post menopause (%)	37	34	33	46	36	37	0.6
Smoking habit (%)
Non-smoker	86	83	83	91	80	90	0.2
Current smoker	11	13	15	8	15	7
Ex-smoker	3	4	2	1	5	3

SD Standard deviation

^aDifferences among residential areas were tested by analysis of variance or the χ² test