Pregnant women have long complained that their baby bump makes them forgetful.
Now a researcher has claimed there may be scientific truth in this 'baby brain' syndrome - and that there is a very good reason why expectant mothers develop short-term memory loss.
The suggestion is that women's brains change during pregnancy so that they will be better able to concentrate on their newborn's needs after the birth, with the result that they become less focused on other things, such as where the car keys might be.
Laura Glynn, a psychologist at Chapman University, California, claims that these changes may be brought about by massive fluctuations in women's hormones as well as tiny movements by the foetus.
Dr Glynn has carried out extensive research on already published studies that look at how women's brains and emotions change during pregnancy.
She says there "may be some cost" of these changes - such as absent-mindedness - "but the benefit is a more sensitive, effective mother".
Dr Glynn also says that just the slightest movement of the foetus in the womb can affect a woman's brain and make her become more sensitive. She claims that even though the woman may not be aware of these movements they will raise her heart rate.
"Pregnancy is a critical period for central nervous system development in mothers, yet we know virtually nothing about it," said Dr Glynn, whose research is published in the journal Current Directions In Psychological Science.
She also says that cells from the foetus will pass into the mother's bloodstream which will also affect the way her brain works.
"It's exciting to think about whether those cells are attracted to certain regions in the brain," she added.
There has been considerable debate in recent years among academics as to whether 'baby brain' really exists. Last year Australian scientists who studied 1200 women claimed there was no evidence to suggest that they had become any more forgetful.
The researchers made women sit memory tests before, during and after pregnancy and found there was very little difference in the scores.
In fact the study claimed that women 'tricked themselves' into thinking they were becoming more absent-minded simply because they had been told this was a likely symptom of pregnancy.
But Dr Glynn insists that we do not know enough about what really happens as there has so far there has been very little research into what actually happens to women's brains during pregnancy.
- DAILY MAIL