Season of birth is not associated with age at menarche in young adults from Central India

Abstract

Objectives: We aimed to test whether birth season is associated with age at menarche in the sub-tropical climate of Central India where temperature and photoperiod differences between seasons are very small.

Methods: Date of birth and age at menarche were collected for 330 female students of Central University, Sagar. The impact of birth month and birth season on age at menarche was analyzed using ANOVA and time-to-event analysis with the use of the Kaplan-Meier curve.

Results: ANOVA, Kaplan-Meier estimation and Cox Proportional Hazard did not show statistically significant differences in age at menarche according to birth month and birth season.

Conclusions: Constant sun exposure during the whole year, related to a stable vitamin D amount and to equal access to fruits and vegetables, may translate into a lack of association between seasons and age at menarche.