There is much to suggest that both girls and boys become sexually mature faster, if they do not live together with their father during childhood. For girls in particular, the longer they live without their father, the earlier their puberty. This is put forward by research results from Aarhus University.

2021.01.13 | Helle Horskjær Hansen

Research suggests that the children from separated families may already be vulnerable to mental health issues, behavioral problems and overweight, and according to Anne Gaml-Sørensen, early puberty can therefore represent an extra risk for the mental and physical health of these children.

Young people in Denmark are today significantly younger when they begin puberty than they were just a generation ago. And this can be a problem. Because earlier puberty can lead to a number of diseases later in life, such as breast cancer, overweight and psychological problems. A study from Aarhus University now suggests that girls who grow up without their fathers enter puberty earlier.

"We compared children who didn’t live together with their father from different points in their childhood with children who lived together with both their mother and father throughout childhood," says PhD student Anne Gaml-Sørensen, who is one of the researchers behind the study.

She emphasises that the research did not look at factors such as the significance of being born to a surrogate mother, being part of a different form of family than the nuclear family, or growing up in a stepfamily. The results have just been published in the scientific journal Child Development.

Earlier puberty

The figures from the study show that on average, girls entered puberty approximately three months earlier, if the father did not live with the mother during pregnancy. The same was true if they did not live with their father at any time during their childhood. If the girls did not live with their fathers from birth to the age of five, they entered puberty on average approx. two months earlier, while if they did not live with their fathers from the ages of six toten, they entered puberty one month earlier.

Boys entered puberty up to two months earlier, if they did not live with their fathers from the ages of six and ten. They entered puberty approx. one month earlier, if they did not live with their fathers from birth to the age of five.

"We examined possible explanations for these associations. The results did not change when we took into account whether the father spent a lot or very little time together with his child when it was aged around a year-and-a-half, the degree of well-being in childhood, as well as the child's BMI at the age of seven, which are all factors that would otherwise be expected to explain the correlation with earlier puberty," explains Anne Gaml-Sørensen.

Stress also has an effect

In the study, the researchers took many different factors into account which could be expected to affect the stability and degree of stress in childhood.

"However, not everything is measurable, so it’s possible that there are still conditions which can affect children’s well-being during childhood and thus explain the correlation with earlier puberty," says Anne Gaml-Sørensen.

The researchers also point out that in the study, they did not take into account whether the children experience a stable and close relationship with a father who does not live in the home, or conversely, whether the children experience a relationship to the father they live together with which is distant and full of conflict.

“The degree of stress and stability in childhood can therefore be experienced differently regardless of whether the father is absent or not,” acknowledges Anne Gaml-Sørensen.

"However, this does not change the conclusion of our study," she continues.

The researchers have used data from the Danish National Birth Cohort and puberty follow-up including almost 16,000 children. In the survey, pregnant women in their first trimester answered whether the father was absent during pregnancy, and at the age of 11 the children stated whether, and if so when during childhood, they had not lived together with their father. Information on the children's pubertal development was collected from the age of 11 until 18 via biannual questionnaires.

Different forms of family examined

A total of 1355 children experienced that their father was absent before they turned six, and 884 experienced that their father was absent from the age of six until they turned eleven. In the study, the researchers also found that 2.1 per cent of all future mothers did not live with their partner during pregnancy. A total of one per cent of the children never lived with their father up to the age of eleven, which is when they were asked.

"The low proportion of children with an absent father from pregnancy and from birth means that there are statistical uncertainties associated with the results we found," emphasises the researcher:

"The next step is to examine whether other family structures or sibling relationships affect the relationship between the father's absence and an earlier age of puberty. We also wish to look at whether there are differences between the forms of family in which there isn’t a father, and families where the children don’t live with their father because the parents are divorced."

___________________________________________________________________________

Puberty

In girls, the first outward signs of puberty are that the breasts begin to grow. Menstruation typically comes a couple of years thereafter. In boys, the first outward sign of puberty is that the testicles begin to grow. The beginning of a pubic hair is also one of the first signs of puberty. The researchers in the study measured different signs of puberty. Girls: Breast development, pubic hair, axillary hair, acne and menstruation. Boys: Growth of the testicles, pubic hair, hair in the armpits, impure skin, age at voice break and age at first ejaculation.

___________________________________________________________________________

Background for the results

• The study is a cohort study in the Danish National Birth Cohort ‘Better Health in Generations' - www.bsig.dk.
• The research is financed by the Research Council for Medical and Health Sciences, the Independent Research Fund Denmark and Aarhus University with grants awarded to Professor Cecilia Høst Ramlau-Hansen.
• The scientific article can be read in Child Development.

Contact

PhD student Anne Gaml-Sørensen
Aarhus University, Department of Public Health
Mobile: (+45) 4086 8183
ags@ph.au.dk

Professor Cecilia Ramlau-Hansen
Aarhus University, Department of Public Health
Mobile: (+45) 2629 5715
chrh@ph.au.dk