Anything to help baby gain weight?

I'm 35 weeks and 2 days and my baby is only 3 pounds . At first I wasn't worried but now I'm starting to panic knowing that he'll be a preemie . I don't want him to be hooked up to machines and not be able to come home with us when I'm ready to leave the hospital 😔 . Is there anything I can do to help him gain weight before he's born?