Researchers at the Australian National University believe they have evidence that forgetfulness in pregnancy is a myth.
Research, published in the British Journal of Psychiatry suggests the phenomenon of 'baby brain' may have more to do with expectations about the effects of pregnancy.
Professor Helen Christensen says the fact pregnant women believe they will forget things, is probably the reason they do.
The ABC reports she says it was an idea she could relate to, from personal experience.
"I've had three children myself and I do think about the literature I read at the time which was suggesting negative things that were going to happen to me," she said.
"When you are pregnant it's very salient, you can always blame something on pregnancy. If you forget your keys you just go, 'Oh gosh it's because I'm pregnant'."
Extent of tests
Professor Christensen said women in the study were tested for speed of thought, long and short term memory and flexibility of thinking.
She said they are part of a larger study in which the tests were conducted at four year intervals.
Professor Christensen said her team decided to compare the results for women who happened to be pregnant at the time of the tests with earlier results, to determine whether there was any difference.
She said studies of other species, including rats, suggested the common beliefs could be wrong.
Professor Christensen said that while there was no evidence humans become smarter during pregnancy, there was no sign of deterioration either.
She said the team was concerned previous studies may have been biased because they recruited women who were already anxious about pregnancy.