New mothers will have to find another excuse for getting in a muddle.
Scientists say that 'baby brain' is a myth and, if anything, having a baby sharpens the female mind.
Far from turning it to mush, there is growing evidence that motherhood primes the brain for empathy, reasoning and judgment.
Mothers are also more assertive, better able to cope with stress and may be better at multi-tasking.
All of this could make them better workers - and an attractive prospect for employers.
Dr Kelly Lambert, a US expert on the flexibility of the brain, said: "Being able to be more efficient in your decision-making, being emotionally resilient, maybe being able to engage in different strategies to solve a problem - that sounds like a wonderful executive or manager to me."
The idea that pregnancy addles the mind is widespread, with up to 80 per cent of mothers-to-be saying they find it trickier to remember phone numbers or string together a complex sentence.
Add to this research showing that the brain shrinks by up to 7 per cent during pregnancy, and it is easy to conclude that 'baby brain' is real.
However, the brain soon bounces back. It not only expands to its former size but areas key to reasoning, judgment, empathy and regulating emotions become supercharged, this week's New Scientist magazine reports.
Craig Kinsley, a neuroscientist in the US, said that this proves that "pregnancy is not just some minor event". He added: "These changes represent a separate developmental period every bit as important as sexual differentiation or puberty."
Other scientists say that the idea of baby brain may be so ingrained that pregnant women and new mothers are extra-alert to memory lapses. And while they happen no more than usual, the woman may notice them more and therefore think they do.
The experts argue that women should resist the stereotype that their brain is going to turn to mush and start believing in themselves.
Sally Adee, features editor at New Scientist, said: "Starting in early pregnancy I became increasingly nervous about what would happen to my brain after having kids. Would I stop caring about my job - or worse, keep caring but no longer be capable of doing it?
"After returning from maternity leave, I began to notice unexpected changes. Where I used to be a fairly anxious person, after having my twins it was much harder to rattle me.
"My to-do list also seemed to evaporate more readily. When I started looking into the science behind all this, I found researchers had uncovered some really surprising changes that maternity causes in the brain."
- Daily Mail