Girls who live in stable, supportive homes may experience puberty later than those who come from more stressful backgrounds, US research suggests.
Early puberty among girls is becoming increasingly common
A study of 180 girls from preschool to the age of 10 found those from families with less marital conflict tended to mature later than some peers.
The Child Development study is the latest into what may cause early puberty, an increasing phenomenon.
But experts say it is very hard to detangle many contributing factors.
The study from the Universities of Arizona and Wisconsin-Madison found parental supportiveness, less marital conflict and depression may play a key in the later onset of puberty.
"Quality of parental investment emerged as a central feature of the proximal family environment in relation to the timing of puberty," said Bruce Ellis of the University of Arizona, lead author of the study.
They speculated in more stressful environments, children are forced to grow up quicker, and adapt their sexual development in response to the conditions in which they live.
Early development risks
But the researchers also found that that those children whose mothers had started puberty later, whose families were better off - at least when the children were very young - and who had a lower body mass index (BMI) at age eight matured later.
Being heavier is one of the factors increasingly seen as contributing to earlier puberty, while genetics has long been held as having a major impact.
Children who live in supportive homes may well also be wealthier and enjoy better nutrition.
"But they still may have found something," says Professor Fran Ebling of Nottingham University's School of Biomedical Sciences.
"Stress and how the body responds to it may well play a role in the onset of puberty, although whether children live more difficult lives than they did in the past is a matter of some debate."
The "normal" age for a girl to show the first signs of puberty is generally accepted as 10 and above, but studies now suggest that as many as one girl in six matures before the age of eight - 18 months earlier than their mothers.
There are thought to be risks attached. In addition to early puberty being linked to certain cancers, difficulties may also arise when a girls' mental development is out of step with her sexual development.
"For one this can be very emotionally disturbing for the child, and it can also pave the way for abuse with earlier sexual activity and pregnancy," Professor Ebling said.