Growing up fast

They act more knowing than earlier generations at their age, but are kids really maturing earlier? GRAHAM REID looks at the research.

At any shopping mall on any weekend you see them. The preteen girls in tight tops and bum-hugging jeans looking as confident and mature as their big sisters in high school.

They can swear just like real adults, and appear streetwise and savvy about sex.

They giggle at that group of surly looking boys, but the knowing exchanges tell you that even at this early age the game of sexual attraction is tentatively being played out.

Kids are growing up fast these days. You know it's true. Ask any teacher. Ask yourself what were you like at their age.

There is considerable anecdotal opinion that children are maturing earlier than they were a century, or even a couple of decades, ago. But often it is based on the evidence in shopping malls rather than hard data.

So when Professor Jean Golding of the University of Bristol's Institute of Child Health released findings this year on what appeared to be children going through puberty earlier than previous norms, it was seized as a rare example of research in the field.

On an initial sample of 1150 8-year-olds in Avon, she found one in six girls had started puberty with the signs of breast buds, pubic hair or both. One in 14 boys had pubic hair.

From these bare facts, large assumptions were made.

On the web at puberty101.com, an otherwise responsible site, the lead page opened with the question: "Do you think your child is too young to view this site? According to recent research, one out of six girls starts puberty by age 8. It is tougher than ever being an 8-year-old ... "

This leap from a small sample into a sociological presumption is typical of the myths and misinformation surrounding changing patterns of adolescent development. If they are changing at all.

It isn't easy to get clinical evidence of precocious puberty. And because puberty is differentiated into subtle, distinct phases - known as Tanner Stages - through which individuals pass at different times, there is no clear demarcation between the pre and post-pubertal.

Boys, in as much as we can generalise, tend to go through puberty 18 months to two years later than girls and often take longer to complete the transition. Girls complete it in around three years.

New Zealand studies show the onset of menarche (menstruation) has fallen since the 19th century when the mean age was 16 to 17 years.

In a 1992 survey of students from three high schools in Dunedin, 283 girls with an average age of 16.5 years were questioned. The average age of menarche was 12.6 years. In a further study in 98-99, 106 girls among 200 studied reported similar onset of menstruation, 12.8 years. Not dissimilar, in fact, from studies in other Western societies.

Golding's British findings were useful, say those in this country who are looking at the apparent earlier onset of puberty. However, our distinct cultural makeup, diet and societal conditions mean that while such international research is of interest, any trends, if they are discernible in the small sample groups, may not be directly transferable to local conditions.

It is accepted in developmental anthropology that different biological subgroups have different rates of maturation. It is acknowledged that many Maori and Polynesian children start the first stages of puberty earlier than their European peers.

Yet there is little specific and ongoing comparative research in an area so important for parents, teachers and health professionals.

"There is a very great gap in adolescent health research," says Diane Murray, a public health nurse and member of the Child and Youth Team, Auckland Health Care. "We are all so busy trying to maintain the status quo of health care we don't have the luxury of going into this area much."

It is also a subject with innate difficulties: it involves privacy issues, areas of social sensitivity and cultural mores.

"Can you imagine how many hui we'd have to go through?" says one doctor who works in the field. "And you can't simply go round looking down kids' pants."

Auckland paediatric endocrinologist Dr Wayne Cutfield also notes, "We don't really know the mechanism which triggers puberty. What we do know is if a child is heavy for their age they do tend to develop earlier."

Changing diet is a well-established contributing factor. What we are eating - good or bad - is making us heavier. Lack of exercise is therefore also a factor. Delayed puberty is frequent in malnourished or chronically ill children. Improved nutrition will reverse the trend in most cases.

"Fatter individuals tend to show earlier onset of puberty," says Dr Ailsa Goulding of Otago University. "Rising obesity in childhood may explain or contribute to trends of the falling age of onset of menarche seen in many countries."

Dr Sue Bagshaw, of Family Planning Southern Region in Christchurch, and the senior medical officer at the Youth Health Centre, acknowledges the clinical impression is that menstruation is happening earlier, the average age somewhere around 12, but can be down to 11 in some girls.

But it is often unhelpful, and can be a mischievous misrepresentation, to blur the boundary between budding breasts and menstruation.

When Golding released her findings, an Observer article used it as springboard into discussing adolescent sex.

"Just as some of our children are said to be drowning in premature hormones," wrote Barbara Ellen, "so is society reeling from the prospect of hordes of 'horny' children, some as young as 10, having sex in the streets."

This was some distance from Golding's cautiously expressed findings.

"First of all the study that was reported," she says, "concerned children at the age 8 who replied (or their parents who did) to a question on early stages of puberty. Here we were talking, not about menstruation, but about the first signs of budding of breasts or the first pubic hair.

"The wild extrapolations ... by some of the British press to assuming that children were sexually active at an early age is bizarre."

Golding, who has presented numerous papers on various aspects of child health, also cautions there have been too few comparative studies to allow researchers to conclude anything.

"I would say there's no clear scientific evidence from our study that puberty is getting earlier, the evidence is purely anecdotal. Primary schoolteachers are noticing earlier maturation - or is it just that they are becoming aware of it?"

Just as Golding's research suffered misrepresentation, so did that by Marcia Herman-Giddens, whose findings appeared in the April 97 edition of the American journal Paediatrics.

Herman-Giddens surveyed 17,077 girls and found many were "developing pubertal characteristics at younger ages than currently used norms."

Statistically she found a mean age of menarche for white girls was 12.8 years and African Americans 12.1 years.

The Washington Post headlined its coverage, "Girls Beginning Puberty Earlier, Study Finds." In the story, however, it accurately reported the less sensational fact, "the age at which girls first menstruate hasn't changed much since 1950."

This is in line with British opinion, according to Dr Russell Viner, a consultant in adolescent medicine at Great Ormond Street Hospital and University College in London. There were trends to earlier puberty in the first half of last century, but since then figures have been static at between 12 and 13 years.

There is consensus that that is also true in New Zealand. The age of the onset of puberty is certainly younger than it was a century ago, but no data supports the idea that it has been in freefall since.

As Cutfield notes, if we assume the onset of puberty to follow the standard bell curve, then the merest shift will allow for increased numbers and therefore visibility. But the numbers reaching puberty early remain small and, just as those who do not pass through it until later, are exceptions.

To assume that an early onset of puberty equates to early sexual activity and maturity is dangerous.

The girl in the mall wearing tight jeans may have budding breasts, but she is perhaps no more emotionally mature than her classmates who collect Pokemon stickers.

"Just because someone is getting sexual feelings," cautions Bagshaw, "does not mean they are acting on them."

It could be criminal, literally, to assume so.

Researchers are sensitive that findings can be manipulated to give comfort to paedophiles or those who would exploit children for commercial gain.

But as Golding notes, "whether [puberty] is getting earlier or not, I think the evidence is that parents and teachers are not quite prepared for it when it does happen. Consequently, I do think there is a need for information to be in the public domain."

The Centre for Youth Health in South Auckland is undertaking a major survey of adolescent health. However, the specific issue of puberty is difficult: identification of pubertal change would require illustrations for survey individuals to compare their growth against, there would be a lengthy process of consultation with parents and care-givers for such graphic representation to be approved of ...

Only one question out of 500 is about pubertal change.

Researchers across the spectrum also agree that data about pubertal development should be interpreted cautiously. Anyone who interprets a slight demographic change to conclude that children are maturing earlier needs reminding of an important qualifier.

Occasionally "some" can be a very big word.