Girls who have disrupted childhoods get pregnant younger, study suggests

Let's think about this, how do these factors affect each other? it's not just breastfed.

- Lilac

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Girls who have disrupted childhoods get pregnant younger, study suggests
by Alok Jha

Not being breastfed, an absent father, moving house frequently and lack of involvement of parents in upbringing all brought forward age of first pregnancy

Girls who are not breastfed as babies or who grow up without a father are likely to have their own children earlier, according to a long-term study of more than 4,500 women across the UK.

The researchers looked at four kinds of dirsuption that might affect the family lives of young girls and found that each one brought forward the age at which they first became pregnant by six months on average.

The study underlines how setbacks in childhood can continue to have an impact into adulthood.

"The early environment matters a lot because it calibrates what kind of world you're living in and what kind of resources you have available to you," said Daniel Nettle, a behavioural scientist at the Institute of Neuroscience at Newcastle University, who led the work. However, he stressed that children could rise above problems during their upbringing.

The study found that even after controlling for major differences such as the parents' income and social class, four factors during upbringing had an impact on the age at which a woman had her first child: whether she was breastfed; how involved her parents were in her upbringing; whether her father was present; and whether her parents moved house regularly.

The key message, said Nettle, is that what happens to children early on in their lives is hugely influential. "As a society, we should never forget that. If you get girls when they're 14 or 15 and say, 'Hey girls don't have babies young', it may not do a lot at that point if, in fact, there have been more influential events much earlier in their lives that set them on a path towards a desire to have short time horizons and have babies young. A lot of those things are to do with stress and wellbeing of kids in deprived areas."

Rather than just telling girls to use condoms, he added, authorities should think much more about the context of people's early years. The research is published today in the Proceedings of the Royal Society B.

Nettle's team used data from the National Child Development Study, an ongoing longitudinal study of all people born in the UK between 3 and 9 March 1958. The cohort has been repeatedly surveyed to gather information about family life and health. Their parents and teachers have also been interviewed to add independent sources of information about their lifestyles.

In his study, Nettle focused on 4,553 women in the cohort who had provided details of their first pregnancy and looked at four potentially disruptive factors in the first seven years of their childhood. Each factor was given a numerical value in the researchers' analysis. In the case of family moves, Nettle calculated whether the child moved home more times than average for a child in that particular area. Fewer moves than average gave a child a "no disruption" score of 0, more moves than average would give a "disrupted" score of 1.

Nettle's results showed that low paternal involvement in the first seven years of a girl's childhood meant an average reduction in the age of first pregnancy of 0.74 years; prolonged separation from a mother in childhood entailed a 0.64-year reduction in first pregnancy. And the effects could be added together, so that if a girl had two of the disruptions to her early life, her age at the time of her first pregnancy was around a year earlier than average. Having all four disruptions brought forward the age of first pregnancy by around two years.

Nettle acknowledged that the nature of the study meant it was hard to be absolutely sure that the early life factors were responsible for the age shift, but he was confident that his research had controlled statistically for other factors such as income and education.

He said the results could be interpreted from an evolutionary point of view because it makes sense to have babies earlier if childhood is disrupted. "If your early world is full of stress, that may calibrate you onto a pathway of develop fast, don't think too far ahead about the future, get on with stuff at an early age. That makes perfect sense – if your environment is full of stress and danger, you probably should do that."

Nettle's work supports similar results found in other mammals, such as rats and rhesus monkeys, which showed that the reproductive schedules of females can be influenced by environmental conditions during their early development. "Female rats whose mothers are kept under caloric restriction during pregnancy reach puberty earlier than controls," write the researchers in the Royal Society journal. "Female rhesus monkeys that experience poor maternal care develop an increased interest in infants during the juvenile period, suggestive of accelerated reproductive schedules."