Anecdotal evidence suggests that many women feel that pregnancy produces memory problems and it has been suggested that this effect may affect 50%-80% of pregnant women. Earlier research showed a reduction of about 4% in brain size during pregnancy, but this returned to normal after giving birth. Further research showed a reduction in the volume of the hippocampus in pregnancy, which could explain the reported memory deficits (Kinsley, 2006). Galea’s (2008) studies show a temporary pause in hippocampal growth during pregnancy and lactation and a meta-analysis confirms that pregnant women did slightly worse than matched non-pregnant controls on memory tasks that involve executive functioning, such as higher-level thinking processes for creating and achieving goals, and that this effect lasted for up to a year after giving birth. Does this mean that pregnancy, giving birth and breast-feeding are bad for women’s memory? No, because studies have also found that mothers do better than non-mothers in cognitive tasks such as learning and memory, so the cognitive changes of pregnancy must reverse. What is the point of these changes? Some researchers suggest that the large hormonal and lifestyle changes of pregnancy, childbirth and lactation are the cause of the temporary deficit, and that the brain is having downtime, a sort of pause, as other functions are more important at this time. Furthermore it has been suggested that there could be evolutionary advantages to the cognitive enhancement post-birth, either because the brain and hormone changes enhance abilities to fend off predators, also to leave the nest to find food and return quickly so their young aren’t attacked – or that these changes reduce the mothers’ fear and anxiety so they can better face such challenges. Of course, these are hypotheses, and not everyone agrees this would hold true for humans. Non-human animal studies do support these hypotheses, and also that as mothers age their brains retain cognitive function better as well as showing less plaques in the brain – structures which in humans lead to the development of Alzheimer’s disease.

Kinsley, C., Lambert, K.G. (January, 2006). The maternal brain. Scientific American 72–79. Pawluski, J.L. & Galea, L.A.M. (2008).The role of reproductive experience on hippocampal function and plasticity. In R.S. Bridges (Ed.) Neurobiology of the Parental Mind, Elsevier, San Diego.