Baby brain? Forget it. Becoming a mum can sharpen cognitive function

It’s common for new mums to lament the fact they feel dazed and forgetful after having a baby. Known as “baby brain”, this is experienced by four out of five women, says Sydney-based neuroscientist Dr Sarah McKay.

But McKay doesn’t believe a woman’s brain is to blame for this feeling. Instead, she says, evidence points towards an improvement in women’s brain function both during pregnancy and after giving birth.

She says the first meaty piece of research supporting this idea was published in the journal Nature Neuroscience in 2017. That study found that during a first pregnancy, a woman’s brain changes in structure, primarily in the networks involved with social cognition. “That particularly allows us to tune into the social cues of this new little human in our lives,” McKay says.

Further research echoed those findings, showing that the brain networks of new mothers “become much more flexible and efficient”. That allows new mums to digest information more rapidly, meaning their learning curve becomes “a whole lot less steep” than it otherwise would be. “So it’s almost as if a window of plasticity in the brain opens that enables us to react and respond to
the baby,” McKay says.

Biologically, it makes sense that the brains of new mums are firing more efficiently than ever, rather than suffocating under a fog of baby brain. McKay says that’s evidenced in the mammalian kingdom, where “cognitive enhancement” in new mothers is routinely seen. For instance, McKay says, in animals that hunt, new mums become better predators. Those that need to remember where nuts and seeds are become better at navigating, and those that rely on smell experience enhanced olfactory abilities.

Yet many human mums feel that their memory takes a hit during this transition. McKay says that when those women are brought into the research lab, “occasionally some studies will find a slight reduction in memory score, but it might only be a point or two. But many other studies find no changes, and we’ve also got studies that show memory enhancement in the third trimester of pregnancy, particularly memory for baby-related items.”

In explaining all of this in her new book, Baby Brain, McKay doesn’t want to invalidate the experience of those who feel their cognitive abilities take a dive during early motherhood. Instead, she wants to offer a different lens through which to view the issue. Rather than being a problem with a woman’s brain, she believes the problem lies in society’s expectations.

McKay says gender stereotypes, the pervasive notion that women should expect a dip in cognitive function after birth, and the weight of emotional labour involved in being a new mum all play a role in what we think of as “baby brain”. (Lack of sleep, of course, can also play a part.) But instead of unpacking the myriad factors that contribute to this phenomenon, McKay says new mums are often quick to blame their brains for how they feel.

So when a mother in the newborn period feels she can’t “do it all”, she’ll often internalise the idea that her hormones had a detrimental effect on her brain function. But, as McKay says, “You can’t be expected to recall all those emails when you’ve got an entire new human in your life and you’re biologically primed to focus on them.”

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