Stress factor... Even relatively minor, everyday stress during pregnancy may affect the brain of the growing foetus, study finds.

Even relatively minor, everyday stress during pregnancy may affect the brain of the growing foetus and cause problem behaviour by the time the child reaches pre-school age, according to Australian research that suggests the psychological effects of financial troubles and personal conflict may start even before birth.

Previous studies have shown the children of mothers who experienced extreme trauma during pregnancy - such as those who were in New York during the September 11 attacks - were less well-adjusted.

But the new study from Western Australia demonstrates the same effects may begin if the mother experiences lower-level stresses, such as pregnancy problems, bereavement, relationship difficulties, job loss, money worries or moving house.

Monique Robinson, a research officer at the Telethon Institute for Child Health Research, led the study, in which nearly 3000 women in mid and late pregnancy were questioned about whether they were experiencing any of 10 potential stresses, and later correlated their responses with their children's behaviour.

She found that when children were two years old the likelihood that they would be disobedient and aggressive increased in proportion to the amount of stress their mother had experienced while pregnant. The same link was still evident by the time the children reached five, though it was less pronounced.

The effects might be the result of stress hormones triggered in the mother entering the bloodstream of the child before birth, Ms Robinson said.

"The last thing I want is for these results to come out and for people to think, 'Now I'm stressed about being stressed'," said Ms Robinson, whose study is published in the Journal of Child Psychology and Psychiatry.

Instead, people needed to develop greater sensitivity to pregnant women's needs.

"In general, pregnancy is a time when there is a lot of pressure on women to do the right thing," Ms Robinson said. Inflexible notions of how pregnant women should behave - such as overly prescriptive dietary advice - could create an atmosphere of anxiety even for women whose social circumstances were good.

Frank Oberklaid, Director of the Centre for Community Child Health at Royal Children's Hospital, Melbourne, said "we know that stress in the environment is bad for the infant's brain", and the new findings, "confirm that we need to pay attention antenatally".

But it was possible that women who said they were stressed during pregnancy might be more susceptible to stress during their children's early years.

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