The link between father absence and earlier puberty in girls has been found in previous research, but most of those studies relied upon recall of the girls' first periods, and few examined the contributions of body mass index, ethnicity and income.
In this new study, researchers recruited 444 girls ages 6-8 through Kaiser Permanente Northern California, and have been following them annually. Their analysis was based on the first two years of follow-up. They considered signs of puberty that occur before the start of menarche. In interviews with the girls' caregivers, the researchers asked about the residents in the girls' homes and their relationships to the children.
Among the girls studied, 80 reported biological father absence at the time of recruitment. Contrary to what the researchers expected, the absence of a biologically related father was linked to earlier breast development for girls in higher income families those having annual household incomes of $50,000 or more. Father absence predicted earlier onset of pubic hair development only in higher income African Americans families.
The mechanisms behind these findings are not entirely clear, the study authors said. Evolutionary biologists have theorized that the absence of a biological father may signal an unstable family environment, leading girls to enter puberty earlier.
Another theory that has been posited is that girls without a biological father in the home are exposed more to unrelated adult males specifically, the pheromones of these males that lead to earlier onset of puberty. However, in this study, the presence of other adult males, including stepfathers, in the home did not alter the findings.
It is also unclear why father absence predicted early puberty only in higher income families, particularly for African American girls.
|Contact: Sarah Yang|
University of California -- Berkeley