Most of what your brain is doing is electrical, but actually chemicals and hormones play a huge role in the brain. Now obviously that plays a role in emotion, but actually emotion plays a huge role in cognition and thinking of all kinds, including memory and every other neuro function.
One way into this is to look at periods. If you measure any aspect of cognitive function, or indeed physical function, of a menstruating woman and plot it over months, you’ll find her time for a 100 metre sprint or a marathon, her speed of memory function for simple tasks, her arithmetic ability, how she responds to emotions situations or how good she is at finding her way through mazes, all of these things change over the course of a month during her natural cycle.
And equally, if you take a man, after a road rage incident for example or another stressful event, and then ask him to do a mental calculation or recall something, the hormones in his body affect his ability to complete that task. So all of our functions all the time is partly driven by our hormones or conditioned by our hormones - male or female.
As such, it wouldn’t be surprising to learn that women’s brains functions differently when they’ve got a particular mix of hormones running around them when they’re pregnant.
"Will her brain be functioning differently when she’s pregnant to when she’s not? Yes"
What’s true though about the menstrual cycles and cognitive function is that there is no simple relationship. Different women exhibit different kinds of fluctuations in cognitive function over their menstrual cycle. And so what there isn’t is a single simple thing that happens to a woman’s brain when she is pregnant. But will her brain be functioning differently when she’s pregnant to when she’s not? Yes. Will that difference be the same for all women? No. Will it be the same through pregnancy? No. It’s the same with men. Do all men act the same when you get them really pissed off? No. Do all men act differently to how they would have acted before they got pissed off? Yes.
It’s the same with nutrition. What you eat and drink has an affect on your brain function and that can be measured in almost any way you like. They all make a difference, but the difference is not consistent.
"Yes, there are differences on average, but the variability within the groups is much bigger than the variability between the groups"
So we can say that as a concept ‘baby brain’ exists, but it will be different for each pregnant woman. It’s the same between men's and women’s brains - if you looked at all the brains in the world you would be able to identify a difference between men's and women’s brains, but the variation between different women’s brains is much greater than the difference between all women’s brains and all men’s brains. Yes, there are differences on average, but the variability within the groups is much bigger than the variability between the groups.