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".