Dependence between Age at Menarche, Body Composition and Selected Somatic Indices.

The aim of this paper is to analyse age at menarche in Tanzanian girls for associations with body composition and selected somatic indices. The study included 97 girls (71 post-menarche and 26 pre-menarche). Measurements were taken of body height, body weight, waist and hip circumferences. Body composition was analysed for percentages of body H2O, fat, and muscle. The girls' nutritional status and body fat distribution were assessed using the following somatic indices: BMI, WHR (Waist-to-Hip Ratio) and WHtR (Waist-to-Height Ratio). For the post-menarcheal group N=71, backward stepwise multiple regression analysis was performed. Average age at menarche calculated using the recall method for N=71 was X=14.29 years, calendar age X=15.92 years. More than half (57.69%) of the girls in the pre-menarche group had not reached the body weight of 48kg, whereas in the post-menarche group they accounted for 32.39%. As many as 97.18% of the post-menarche girls had body fat content of 22%, compared to 88.46% in the pre-menarche group. In terms of BMI, 74.65% of post-menarche girls had healthy weight, compared to 73.08% in the pre-menarche group. There were no significant differences in WHR or WHtR, which may indicate similar fat distribution in girls prior to and after menarche. The analysis showed that the onset of menstruation is not strictly dependent on reaching a critical point in body weight or body composition.