Objective: To survey age of menarche in Pudong district in Shanghai.
Methods: Data in this study were derived from 56,924 women at age of 20-81 years in screening for cervical cancer between January 2007 and July 2008 in Pudong district. The age of menarche were recorded in a questionnaire. To investigate the trends in age at menarche in different socioeconomic status, the subjects were divided into 12 groups in 5-year birth cohorts. The mean menarche age in each group was analyzed by analysis of variance (ANOVA). The percentage of menarche age at 10-12 years and more than 18 years was analyzed by chi2 method.
Results: (1) The minimum age of menarche recorded is 10 years old, and the maximum is 28 years old, with average age of menarche at 15.7 years. In all groups, the smallest average age of menarche is 14. 6 years in 26-30 years old age group, while the biggest average age of menarche age is 16.5 years in >75 years old group; The difference showed statistical significance (P < 0.01). (2) The percentages for participants with early menarche age (10-12 years old) or late menarche age (>18-year-old menarche) were 1.82% (1034/56,924) and 5.20% (2959/56,924) respectively. However, the maximum percentage for early menarche was recorded in 31-35 years old group (4.45%, 197/4431), only 0.84% (10/1191) of participants in >75 years old group was classified as early menarche. Meanwhile, the lowest percentage for late menarche was 0.38% (17/4431) in 31-35 years old group, and the highest percentage was 14.70% (91/619) in >75 years old group. The changes in the percentages for early menarche or late menarche are significantly associated with age differences (P < 0.01).
Conclusion: The study suggested that the average of onset age of menarche in Pudong district has declined over the past decades in an age-based way, accompanied with the increase of the percentage for early menarche and the decrease of percentage for late menarche.