For generations it was considered an old wives’ tale, the tendency for new mothers to become somewhat scatterbrained for the first few months of parenthood.
A 2018 study published in the Medical Journal of Australia found pregnant women performed worse than non-pregnant women on tasks measuring attention, decision-making, planning, and memory. It was also found that different stages of the pregnancy affect women’s brains in various ways, with most of the ‘decline’ occurring during the first trimester. Study co-author Sasha Davies argues ‘baby brain’ may be “an important adaptive phenomenon” that might help women prepare for raising their children “by allowing their brains to adapt to their new role as mothers”.
Other research found pregnancy even reduced grey matter in the brain which can then take up to six years to repair – though when it does, it builds back stronger. And it’s not the only benefit.
During mammalian pregnancies – including human ones – there is an exchange of cells and DNA between mum and bub that’s known as foetal-maternal microchimerism (named after the chimera, a beast of Greek mythology which was part goat, lion, and dragon). While the maternal cell exchange is thought to last only into early infancy, perhaps to aid with the child’s immune response, research shows that cells from the child can live on
in the mother for years longer, sometimes even for the rest of her life.
The concept of such a physical, everlasting maternal bond is a beautiful one and one that has been observed for decades, but scientists are still uncertain of its purpose – though research does point to it generally being beneficial. Some studies have shown the cells play a part in healing mother’s skin wounds – including caesarean section scars – by helping boost collagen production. Others have shown foetal cells to migrate all over the mother’s body, embedding themselves in organs including the heart, blood, and brain.
But it turns out that that foggy ‘baby brain’ is actually a thing – and it might not be the only thing you think it is.
The cells’ presence in the breast has led to speculation that microchimerism may be a self-serving process to ensure survival by increasing milk supply, for example. And microchimerism has also been associated with lowering the risk of breast cancer.
However, there is also evidence of an increased likelihood of other cancers and some autoimmune diseases, which may explain why women are three times more likely to suffer rheumatoid arthritis than men and are generally at higher risk of autoimmunity – a theory being that the cells are recognised as foreign bodies by the mother’s body, triggering a response by her immune system.
Interestingly, the sex of the baby may even be significant. Though cardiovascular disease appears slightly higher among women hosting male cells, their overall mortality rate was 60% lower owing to lower incidence of other diseases, including cancer. A study published in International Journal of Epidemiology concluded 85% of the women with male cells lived to 80, versus 67% of those without them. The research also found that male DNA may also help mothers fend off Alzheimer’s.
“There’s so much observation out there,” study lead author Kamper-Jørgensen, an associate professor of public health at the University of Copenhagen, tells the Atlantic. “Having kids protects you from breast cancer, but we don’t really know why. If you have kids, you live longer, but we don’t really know why. Women live longer than men, but we don’t know why. This phenomenon, this may be it.”
