But in reality this doesn't exist, scientists claim.
While those who are pregnant may believe their memory is worse than usual, a study has found that they perform just as well as other women in mental tests.
And it doesn't just apply to memory. Other key skills, including attention span and spatial awareness, are equally unaffected by pregnancy.
With up to 80 per cent of pregnant women saying they suffer memory lapses, the finding could prove controversial. However, the US researchers say their aim is to give mothers-to-be a confidence boost.
However, the US researchers say their aim is to give mothers-to-be a confidence boost.
They said that there is a 'stereotype that your brain is going to turn to mush' when pregnant and that women should resist it.
With previous studies into the existence of baby brain providing mixed results, the team from Brigham Young University in Salt Lake City set out to come up with a definitive answer.
They put 21 mothers-to-be through a battery of mental tests a few weeks before their baby was due and again a couple of months after the birth.
Another 21 women who weren't pregnant and had never had any children also completed the three-hour set of tests.
There were no differences between the two groups in memory, thinking, attention span, organisational or spatial skills.
Whether the tests were taken during pregnancy or when looking after a young baby, the women did just as well as those who had never been pregnant.
However, when asked how they had performed, the pregnant women and new mothers thought they had done worse. They also said they had a lower quality of life and were less satisfied with their lot.
Psychologyprofessor Michael Larson, lead author of the study, said: 'I was surprised at how strong the feeling was that they weren't performing well.
'This feeling of, "I really am doing badly right now" exists despite the objective evidence that they aren't.'
更多英语新闻
