When and how do adolescent girls in Japan become aware of premenstrual symptoms from menarche? A cross-sectional study among senior high school students

OBJECTIVE: To investigate the interval from menarche to the onset of premenstrual symptoms and its relationship with menarche age. DESIGN: Cross-sectional school-based survey. SETTING: Urban areas of Sendai, the largest city in northeastern Japan. PARTICIPANTS: 1422 female Japanese 10th–12th grade senior high school students participated in the survey. MAIN OUTCOME MEASURES: The time of awareness of premenstrual symptoms, and the interval from menarche to the onset of premenstrual symptoms. RESULTS: 1290 students had menstruation and completed the whole survey. The median age at menarche was 12 years (IQR: 11–13 years). The prevalence of self-reported premenstrual symptoms was 49%. The median age at which students became aware of premenstrual symptoms was 15 years (IQR: 14–16 years). The median time from the onset of menarche to awareness of premenstrual symptoms was 2 years. This time was negatively correlated with menarche age ([Formula: see text] =−0.47, p<0.001). A Cox proportional hazards regression analysis revealed that early menarche was significantly associated with a lower cumulative risk of developing premenstrual symptoms (OR: 0.73 (95% CI 0.58 to 0.91)). CONCLUSIONS: High school students in Japan began experiencing premenstrual symptoms at around 15 years old, and within 2 years of menarche. This study suggested that social factors other than hormonal factors, such as early menarche, might be associated with the onset of premenstrual symptoms.