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. Author manuscript; available in PMC: 2015 Feb 1.
Published in final edited form as: Cancer Epidemiol. 2013 Dec 25;38(1):62–65. doi: 10.1016/j.canep.2013.12.001

Table 1.

Descriptive characteristics of menstrual traits by study stage.

Characteristic (years) Stage I: Three State Study Stage II: Beaver Dam Study
N Median SD Range N Median SD Range
Age 1328 54.8 9.6 26–74 1353 61.0 11.0 43–86
Age at menarche 1319 13.0 1.6 8–22 1341 13.0 1.6 8–21
Age at menopausea 462 50.0 5.2 15–59 688 50.0 5.1 24–70
Reproductive lifespanb 455 32.3 7.2 2.0–45.1 683 37.0 5.3 10–58
a

Analyses restricted to women who underwent natural menopause.

b

The reproductive lifespan is defined by the interval between age at menarche and age at natural menopause. Analyses in the Three State Study account for pregnancy related events. SD indicates standard deviation.