Early puberty linked to growing up in poorer homes

In the face of hardship children may be programmed to start the reproductive process earlier. Photo / 123RF

Children from disadvantaged households are more likely to hit puberty early, an Australian study suggests.

In the face of hardship - economic disadvantage, harsh physical environment, or absence of a father- children may be programmed to start the reproductive process earlier.

Boys who grew up in "very disadvantaged homes" had more than four times the risk of starting puberty early, while girls had double the risk, research by Melbourne's Murdoch Children's Research Institute (MCRI) has found.

University of Auckland-based researcher in the team and Liggins Institute Professor Melissa Wake said it was likely the same link could be found in New Zealand children.

"Early puberty may be one of the ways in which social disadvantage gets under the skin and influences children's later life chances, both in terms of economic prosperity and health."

In the study, MCRI researchers surveyed about 3700 children recruited at birth as part of the Growing Up in Australia study, to investigate if social determinants were playing a role.

Parents were asked to report on signs of children's puberty at age 8 to 9 and 10 to 11.

These included a growth spurt, pubic hair and skin changes, plus breast growth and menstruation in girls, and voice deepening and facial hair in boys.

The paper compared the family socioeconomic position of those who started puberty early with others who started on time.

Wake added defining disadvantaged households was a "composite of a whole lot of different indicators", which included parents' education level, the jobs they held, household income and financial insecurity.

At 10 to 11, about 19 per cent of all boys and 21 per cent of all girls were classified in the early puberty group.

"Anything that triggers early puberty is of interest to policy makers."

Lead author, Associate Professor Ying Sun, said ongoing exposure to "extremely unfavourable" household socioeconomic positions in boys independently predicted a four-fold increase in the rate of early puberty.

"In girls, the increase was nearly two-fold, when compared with those from a favourable background."

Sun said their findings raised a possibility that the timing of puberty could play a role in the links between early social disadvantage, and health problems later in life.

"If our research can improve the understanding of these links, we can potentially inform new public health initiatives that improve the health and wellbeing of all children for the rest of their lives."

Disadvantage could be linked to early puberty for evolutionary reasons, Sun said.

Children may start the reproductive process earlier to ensure their genes are passed on to the next generation.

"We now know quite a lot more about the switches for the pubertal process and think that childhood disadvantage is one of a number of factors, including prematurity and being overweight early in childhood that switch the process on."

Senior author Professor George Patton said it was important to understand the impact early puberty could have on the health of children and adolescents later in life.

"Early maturation has links in girls with emotional, behavioural and social problems during adolescence including depressive disorders, substance disorders, eating disorders and precocious sexuality."

Patton said early puberty also carried risks for the development of reproductive tract cancers and cardio-metabolic diseases in later life.

"Given the recent trend towards earlier pubertal maturation in many countries, a clearer understanding of factors influencing pubertal timing is important."

The study was published in the journal Pediatrics.