Jennifer Garner paired James jeans with a flowing top for an easy silhouette. When choosing maternity denim, says Soloman, "Comfort is key, make sure you have enough hip space." Although the elastic panel at the waist will grow with you, it's best to wait until your second trimester before investing in a pair. Says Soloman: "Denim is one item that is difficult to buy early and keep through your whole term because it has less stretch then most other fabrics."