You'll be shoe shopping, as your feet may expand up to a full size during pregnancy. Some of this is due to water retention and some is due to a pregnancy hormone called relaxin, which makes all your joints looser, even the ones in your feet. Pregnant women often suffer from lower back pain, and also tend to lose their balance more easily than the non-pregnant.
All these things make stilettos a difficult—and risky—proposition. That's why the new flats, kitten heels, and chunky-heeled boots are so wonderful. They're stylish, pretty, and safe. After all, when you haven't had a glass of champagne in months, why risk falling on your behind?