Figure 3From: Secular trends in age at menarche and time to establish regular menstrual cycling in Japanese women born between 1930 and 1985 Distribution of early age onset of ovulatory cycles by year of birth. Early age onset of ovulatory cycles means the woman who experienced younger age at menarche at ten years old or younger and started a regular cycle within one year. Cochran-Armitage Trend Test Z = -7.40, p < .0001.Back to article page