Pants and Skirts
During your first trimester, you'll probably be too small for maternity wear but won't quite fit into your regular bottoms. You can use a belly band -- a seamless Lycra band (essentially a tube top around your waist) -- to get more mileage from your current pants and skirts. Put it on over your regular pants to hold them up and cover the unbuttoned waist. You can also wear it over maternity pants that are still too big, making them fit and concealing the extra fabric.
When you're approaching your second trimester, shop for jeans. Choose one dark pair and one light pair that you can dress up or down. You'll feel and look best in whatever style you preferred pre-pregnancy, so if you love those boot legs, stick with them now.
Balance is key when you're choosing bottoms to complete an outfit. Vanessa Knox-Brien, creator of Isabella Oliver maternity wear says, "If you go flowy on top, choose slim, fitted jeans or leggings. If you pick a fitted tee, try a pair of wide-leg trousers."
For lounging around the house, sweatpants are a good choice. Choose elastic, Lycra, or drawstring -- anything adjustable is best, especially since you'll be able to keep wearing it for a few months after you give birth. And don't forget to raid your husband's closet. His boxers and big shirts are perfect for sleepwear.