ABSTRACT
Precise prediction of menarcheal age enables and prepares girls to face the changes they may experience in this period the future. In Iran, there are no available data in this regard yet. This cross-sectional descriptive study was done on 629 girls from 24 provinces of Iran. Relative questionnaires to collect data were filled out with the help of the participant herself and one other family member as well. The stage of maturity regarding telarche and pubarche, percent of body fat were entered based on history taken and physical examinations. For predicting menarche age in cases, the linear regression model was used. In the 454 cases studied, menarche age, mean of age at menarche was 13.18 +/- 0.06 years old [158.2 +/- 0.7 months]. The means of menarche age in grandmothers and mothers of these 454 cases were 12.9 +/- 0.25 and 13.6 +/- 0.14 years respectively. Earlier menarche was observed in girls of lower height [p < 0.001], girls of lower age at the beginning of study exercise [P = 0.019], girls with lesser number of sisters [P = 0.007], or those with lesser number of brothers [P = 0.003], higher percent of body fat [P = 0.037], those with higher body mass index [P = 0.002], and those residing in mountainous regions [P = 0.001]. The regression model showed that the menarcheal age was predictable based on following variables: current height of individual [p < 0.001] height of place of residence from sea level [p < 0.001] number of brothers [P = 0.006] number of sisters [P = 0.008] [P = 0.001, R-square = 0.99]. Lower height, number of family members and residing in mountainous areas in that order are the most useful predictors of age at menarche. In recent decades, apparently there has been a significant decrease in menarcheal age due to improvement in the quality of nutrition the increasing trend seen today could be due to both weak dietary habits and more sedentary life styles or as a response to increased physical and psychosocial stresses