Women were asked during the telephone interview how old (years and months) they were when they had their first menstrual period. Ages were truncated at years because fewer than 5% of women reported a value for months. For women who did not know their age at menarche, it was estimated from their grade in school at the time of their first menstrual period (n=77) or from reporting whether their first menstrual period occurred before, after, or at the same time as other girls their age (n=63). The latter responses were estimated as 11 years, 14 years, and 12.5 years, respectively.
