Family composition and age at menarche: Findings from the international Health Behaviour in School-aged Children study.

For the number of brothers and sisters, almost no indirect effect was found, although direct effects were highly significant for both.

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Performed sensitivity analyses (using a very homogeneous sample of girls living with biological mother and father who had their period between the age of 12 and 13) showing a same size effect of psychosomatic complaints and BMI on the age at menarche, also provide support for the hypothesis that BMI and psychosomatic complaints may be significant predictors, definitely significant correlates of pubertal timing.

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