Baby books get it wrong: being pregnant doesn't necessarily mean being brainless, dpa reported.
Australian National University researcher Helen Christensen has debunked the theory that being with child means being without a full complement of brain power. Along with Canberra colleagues, she tested 1,241 women when they were aged 20-24 and again when they were four and eight years older.
"We took measurements of the women before they were pregnant and compared them to when they were pregnant and also with women who had become new mothers and we found no difference in their levels of functioning before pregnancy and during early motherhood," Christensen said.
"I wasn't surprised because I knew there were biases from the earlier research," she added, noting that previous studies compared pregnant women with women who weren't pregnant.
In the Canberra study, measurements were taken of the same women pregnant and not pregnant and so were more reliable.
Christensen said the myth of what some call "baby brain" might be explained by women being told to expect their mental faculties to fail them.
"Part of the problem is that pregnancy manuals tell women they're likely to experience memory and concentration problems, so women and their partners are primed to attribute any memory lapse to the hard-to-miss physical sign of pregnancy," she said. "Women and their partners need to be less automatic in their willingness to attribute common memory lapses to a growing or new baby."
Not that there aren't changes in mental functioning that might deceive some into thinking that brain power has been lost.
"It's possible that you get this selective attention," Christensen said. "You're more interested in baby-type issues and that distracts you from your task at hand." She said the changes didn't mean pregnant or new mothers had cognitive deficits, only that "it just means you have a propensity to move on to daydreaming or tune in to a different mode of thinking."
Her study Cognition in Pregnancy and Motherhood, which was published in the British Journal of Psychiatry, contradicts an earlier Australian analysis of the literature which said pregnancy impairs memory for most pregnant women.
The 2003 research, led by the University of New South Wales' Julie Henry, said 80 per cent of pregnant and new mothers displayed cognitive deficits for up to a year after giving birth.
Henry, who looked at 14 studies in the field, said pregnant women were "significantly impaired on some, but not all, measures of memory," and that "memory measures that place relatively high demands on executive cognitive control may be selectively disrupted."