A cohort study of correlation between body mass index and age at menarche in healthy Bengali girls.

There are contradictory reports of lowering of age at menarche due to increasing body mass index (BMI) in the population. It is not known if a greater BMI at menarche is associated with a lower menarcheal age in healthy Bengali girls of normal nutrition. In this study the age at menarche was determined in 273 Bengali girls of middle income families. It was assessed whether BMI standard deviation scores (SDS) at menarche, BMI SDS at one year preceding menarche and BMI increments during that year were in correlation with age at menarche. The age of the girls with adequate nutrition was 8-16 years. They were examined for BMI, pubertal breast staging and age at menarche over a 4-year follow-up period. BMI SDS were calculated from National Center for Health Statistics (NCHS) normative data. The median age at menarche of 12.0 (range 10.0 - 16.0) years did not correlate with BMI SDS at menarche or BMI SDS at one year preceding menarche in this cohort. In univariate analysis, BMI increments for a given breast stage did not significantly lower the age at menarche. The change of BMI in the year preceding menarche did not correlate with age at menarche. The age at menarche in healthy Bengali girls of middle income families was similar to that of other Indian observations. There was no influence of BMI increments or that of BMI SDS prior to or at menarche on age at menarche.