Well, I don’t know if it’s the brain power or the gray matter pruning that goes on, but my wife was an absolute space cadet for a while during pregnancy and quite a while after. She’d forget almost everything.
I've read literature that the hormone fluctuations resulting from pregnancy, and from parenting regardless of sex actually trigger the destruction of particular parts of the brain in humans.
This is a long shot, but I've always wondered if it might be genetically related to the part of the brain responsible for "abandon one of the babies to escape predator" type reasoning that you see in animals with litters. Something that would have been selected out of human evolution fairly quickly.
