Confounders
Pubertal stagewas self-estimated on the
basis of Tanner drawings and pictures.31
Until age 9 years, pubertal stage was
assumed to be prepubertal. Migration
background was defined as follows: 1 or
both parents were not born in Germany
and/or had no German citizenship and/
or the German language was not spoken
at home. In addition, age, gender, gestational
age, and study were treated as
confounders.