Statistically, Rebecca who is african american is most apt to experience menarche first. Once the primary sexual organs start to function the adolescents are biologically in capable of reproduction. Menarche does not typically take place until a girl weighs 100 pounds. It seems that the effectiveness of menarche is connected to the buildup of a definite quantity of body fat which is why heavy girls usually menstruate earlier than other girls do. For girls, the normal order of physical changes in puberty is nipple growth, the growth spurt, and menarche and for girls the menarche is the girls first menstrual period.