This might sound silly, but you're going to have a lot of pictures taken of you in the hospital without any makeup, and having a little bit of glam makes you feel a lot better. (momtricks.com)
This may seem silly, too, but you are going to be taking a lot of pictures at the hospital holding your new baby, and since you are going to feel chubby and still fat after they are born, it is always nice to have a little bit of glam to make you feel better! (lifewithmylittles.com)