Your Brain Shrinks

What happens: You don't lose brain cells per se, but as your metabolism changes, your brain restructures the connections between cells, changing in preparation for motherhood. This is probably no surprise to those of you who've experienced "mommy brain," which is a kind of subtle forgetfulness that makes pregnant women put the milk in the cupboard or dump chili powder on ice cream.

Why it happens: Typically limited to the third trimester, mommy brain might actually have evolved as a way of helping you focus on your baby and block out worrisome thoughts. But don't fret about your inability to think straight. In the final 1 to 2 weeks before birth, your brain will begin to increase in size again and build new maternal neural circuits, eventually becoming stronger than it was before and helping you to better cope with your newborn.