Welcome to TCS Margo0609. Please give some more information. Is your cat eating normally, what is she eating? How many kittens has she given birth to and how old are they? should we understand that she is not nursing the kittens at all? If so how are you feeding them?
Is is possible she won't produce enough milk or any milk. It doesn't mean she won't do everything else as a mother cat, she'll probably let them nurse. They won't be getting any milk, so you'll need to be ready to bottle/syringe feed the babies.
Get the nursing kits at a pet store, buy the bottles for when they are bigger, which will be in days. Get the goats milk and kmr that StefenZ mentioned. You'll need it for the kits as well as mom. Oh, and mom will need it even if she produces milk.
It's easy to think the kits are getting enough milk, when they aren't. Do you have a scale to weigh them? A postal or kitchen scale will do. Many do grams as well as ounces.