Pregnancy causes loss of grey matter in specific regions of the brain, including the hippocampus. This is probably due to synaptic pruning. If you show new mothers pictures of their babies, the modified areas of the brain become highly active.
This pioneering work by Elseline Hoekzema, a neuroscientist at Leiden University the Netherlands who is also the pregnant mother of a 2-year-old, is the first to demonstrate widespread anatomical changes in the pregnant human brain.
It also shows that the changes last for at least 2 years. “It opens the door to the possibility that it might cause changes in parenting that might have implications in decision-making and behaviour later in life,” says Mel Rutherford, an evolutionary psychologist at McMaster University in Hamilton, Canada.