In 2016 neuroscientists reported that pregnancy does change a woman's brain and that these changes last for up to two years. These changes are evident in brain scans to the extent that scientists can tell simply by looking at these scans if a woman has been pregnant.
The differences concerned a pruning in the number of connections in the brain which served to help the mother focus more closely on her baby [see here for the details]. However the researchers found no evidence of “baby-brain” in the women they examined. They scored about the same on tests of memory and vocabulary both before and after giving birth. So now you know!