Though women who have felt themselves becoming more forgetful and feeling less onto it than usual will tell you the phenomenon very much exists until now, many academics have dismissed baby brain as a myth.
A new study by Australian scientists from Deakin University looked at 20 previous studies involving over 1,200 women - both pregnant and non-pregnant.
Upon compiling all of the findings, researchers saw declines in pregnant women's cognitive functioning, memory and executive functioning (which includes multi-tasking), particularly in the trimester, SMH reports.
"The declines start to happen between the first and the second trimester, and then look like they stabilise … but are most obvious in the third trimester," Associate Professor Linda Byrne said of the findings, published in The Medical Journal of Australia.
"We are talking about an effect that will be noticeable to the women themselves and it may even be noticeable to people that are close to them," she explains.
"A woman might find that suddenly she has to make notes about things in order remember appointments, or do extra work to remember the things she used to be able to do automatically."
"In the other areas, it could be that they feel less sharp than usual."
Researchers stressed that while the women would notice the changes, they are unlikely to be noticed by people unfamiliar with the women or to affect the woman being able to perform their job adequately.
"Performance remained within the normal ranges of general cognitive function and memory," the study reads.
As for the reason behind baby brain? Researchers suggest it's the body's way of preparing for motherhood and making way for other important skills.
"It looks like the reason pregnant women have grey matter reduction is because they're probably recruiting those areas to more important areas associated with the business of child rearing — so things like bonding, and social cognition," Professor Bryne explains.