Family conditions may affect when girls experience puberty

Early puberty in girls has been found to negatively affect these teenagers’ health in areas such as mood disorders, substance abuse, adolescent pregnancy, and cancers of the reproductive system. Given these findings, it is critical to understand why certain adolescents are at increased risk for early puberty in order to develop effective early intervention and prevention strategies for high-risk youths.

New research shows that greater support from mothers and fathers, as well as less marital conflict and depression (as reported by fathers), can lead to later onset of puberty. The findings, from researchers at the University of Arizona and the University of Wisconsin–Madison, are published in the November/December 2007 issue of the journal Child Development.

The researchers sought to test and extend a 1991 model (developed by researcher Jay Belsky and colleagues) of the role of family ecology in speeding up or slowing down puberty in girls. According to Belsky’s theory, children’s early experiences affect how they mature, with certain stressors in and around the family creating conditions that speed puberty as well as sexual activity. These stressors include marital conflict, negativity and coercion in parent-child relationships, and lack of support between parents and children. According to the theory, children adaptively adjust their sexual development in response to the conditions in which they live.

To test this theory, the researchers investigated the effects of stressors on the timing of children’s development by examining families of 227 preschool children over a period of time. Specifically, they looked at the families’ socioeconomic conditions, marital conflict, parental depression, and supportive versus coercive parenting, through interviews with both mothers and fathers. The study followed the children through middle school, testing the first hormonal changes of puberty–the awakening of the adrenal glands–in 120 of the children (73 or whom were girls) when they were in first grade, and the development of secondary sexual characteristics–such as breast budding and the growth of body hair–in 180 girls when they were in fifth grade.

Children living in families with greater parental supportiveness (from both mothers and fathers) and less marital conflict and depression (but only when reported by fathers) experienced the first hormonal changes of puberty later than other children, the researchers found. In addition, children whose mothers had started puberty later (a genetic factor), whose families were better off when the children were in preschool, whose moms gave them more support when they were in preschool, and who had lower Body Mass Index (BMI) when they were in third grade developed secondary sexual characteristics later than their peers.

“Consistent with the theory, quality of parental investment emerged as a central feature of the proximal family environment in relation to the timing of puberty,” according to Bruce J. Ellis, associate professor of family studies and human development at the University of Arizona and the lead author of the study. “These results replicate and extend previous longitudinal research indicating that higher levels of positive investment and support in family relationships in preschool predict lower levels of pubertal maturation in daughters in the seventh grade.”