Thursday November 15 2007
Age of puberty is linked to many factors
“Girls who live in a happy and stable family mature later and are less likely to develop mood disorders, substance abuse and certain cancers,” reports The Daily Telegraph today. The newspaper reports that in homes with fewer marriage problems and depression, girls go through puberty later.
This story is based on research using data collected during the children’s preschool and early school years. The study found a link between the age at which girls develop secondary sexual characteristics and the parental support they receive during their preschool years. The study is a reliable one; however, a stable family life is just one of many factors that are likely to influence the age of a girl’s first period, and one of these that the study may not have accounted for, is genetics. In addition, the study did not investigate how the timing of puberty is linked to any health-related issues later in life.
Where did the story come from?
Bruce Ellis and Marilyn Essex of the University of Arizona and the University of Wisconsin carried out this research. The study was funded by grants from the National Institute of Mental Health and the MacArthur Foundation Research Network on Psychopathology and Development. It was published in the peer-reviewed medical journal: Child Development.
What kind of scientific study was this?
The study is a prospective cohort study which uses a representative subset of data from children who were included in a bigger study – the Wisconsin Study of Families and Work (WSFW). In the WSFW, pregnant women were enrolled and data were collected, using questionnaires and interviews, about them and their children throughout the child’s infancy and early schooling. For this publication, the researchers were interested in seeing whether family environment influenced “adrenarche” in boys and girls in Grade 1 (age about 6.8 to 7.8 years). Adrenarche is the time when the adrenal glands mature and begin to function. It takes place before puberty, usually at ages six to eight years in both boys and girls.
The researchers were also interested in whether family environment had any effect on secondary sexual characteristics in girls who were aged about 10.5 to 11.9 years (Grade 5). They had information available on a range of different characteristics of these families, including the mothers’ age when her periods started, socioeconomic status, parents’ reports of marital conflict/depression, measures of parental supportiveness, child’s height and weight and so on. Adrenarche was determined in the children by testing for the presence of a hormone found in the saliva. Secondary sexual characteristics in girls were determined using questionnaires to mothers and girls that rated appearance of pubic hair and the breast development stage. Using statistical methods, the researchers determined which of the family factors had an effect on whether the child had reached adrenarche by Grade 1 or whether there were signs of secondary sexual characteristics by Grade 5. They used complex mathematical methods to explore some of these relationships further.
What were the results of the study?
The researchers found that the children who had reached adrenarche by Grade 1 were more likely to be from families where “parental supportiveness” was lower during preschool years. They were also more likely to be from families where father-reported marital conflict/depression was high, though this didn’t seem to be the case when they looked at the mothers’ reporting of marital conflict/depression. They found that socioeconomic status had no effect on adrenarche.
In terms of secondary sexual characteristics in girls, they found that development was delayed in families where there was high parental supportiveness in preschool and a higher socioeconomic status. Overall, they found that later sexual development in girls was predicted by a later age at mothers’ first period, higher socioeconomic status, greater mother-based parental support and higher BMI.
What interpretations did the researchers draw from these results?
The researchers conclude that the results of their study support a theory – ”psychosocial acceleration theory” – which predicts that the higher the quality of parenting in the preschool years, the slower the rate of sexual maturity (shown by lower rates of adrenarche in boys and girls in Grade 1 and less development of secondary sexual characteristics in girls in Grade 5). They say that their findings about marital conflict/depression are not helpful and “further cloud the already contradictory literature” on whether family conflict accelerates puberty.
What does the NHS Knowledge Service make of this study?
There are several points to keep in mind:
- The “model” that the researchers developed was able to show that the later age of sexual development for girls was linked to mothers’ age at first period, BMI, parental supportiveness, marital conflict/depression and socioeconomic status. However, the researchers say that these factors accounted for only 25% of the variation in sexual maturity. There are other factors involved that the researchers have not investigated. One of the most important factors that may not have been fully addressed is genetics. The researchers say that although they tried to consider this by looking at mothers’ age at first period, they “cannot be certain by any means that the effects of biological inheritance have been fully accounted for”.
- As the researchers highlight, the children in their study were all Caucasians. No information is available then about other ethnicities. Both family environment and the timing of puberty are known to vary between ethnic groups.
- There were different parts to the study’s results depending on how the researchers analysed the data. They do not, however, find any link between marital conflict/depression and the development of secondary sexual characteristics in girls. The report in the newspapers may suggest that a link was found, but this is not the case. The researchers did find that mothers’ reports of marital conflict/depression were linked to body mass index and to measures of parental supportiveness. This shows that there are complex interactions going on between the characteristics.
As the authors acknowledge, there are clearly many factors that may predict or even determine the timing of the onset of puberty. Parental supportiveness seems an essential in order to bring up healthy young children and it should be promoted without any need to resort to complex modelling theories.
Sir Muir Gray adds...
Inequality is bad for your heath and the effects start early, even before birth, never mind at puberty. Although most people think of money when inequality is mentioned, inequality in family stability is another aspect that can have adverse effects.