You can buy your own gown for labor and birth. Even if you are wearing a nighty, it is bound to be prettier and makes you feel like less of a "patient" than when you are using a hospital gown. You'll also know that you will be the only person to wear it. The main thing to take into account is that you will obviously require to wear something that provides easy access to your pelvic area. You might also like to buy new jammies for the immediate postpartum period. Fresh, smaller PJs will make you feel cozy after you have given birth. Did you know that there is even such a thing as a special labor skirt?
There are several companies that produce such skirts, and they can also be found on home-made goods websites, like etsy for example. Some labor skirts are made out of the same materials as bikinis, for those women who would like to give birth in water or spend some of their labor in a pool or under the shower. Still, don't be surprised if all your modesty goes out the window when you are in the throws of labor. I, for one, felt so hot and sweaty towards the end of my births that I stripped naked with my first, and ended up wearing a short-sleeved gown for my second. For related stuff, you can check out who to invite into the delivery room, and childbirth preparation watch birth videos on YouTube!