Babies need to be fed a lot more and they need more protein than an adult betta...this is why live or frozen foods are needed. I feed crushed NLS pellets, about 4, twice per day and I feed frozen bloodworms twice per day, a chunk about half the size of a pea each serving. Bloodworms are about 55% protein whereas the NLS pellets say 37% protein. The pellets have vitamins and other things that the bloodworms do not, however, so make sure to feed both.
I do a 40% water change in my 5 gallon aquarium every day for my baby because they do secrete a hormone that stunts growth. Its not just the nitrate levels you're doing water changes for when you have a youngster.
Other than that provide a lot of cover with plants and decor so the baby feels safe.