Regularly weigh your cat and adjust her food portions; this will help her to avoid gaining too much weight during the pregnancy. You should also continue to feed her using the same routine that you've already established: at specific times of the day and in a specific place. Make sure there is plenty of water available for her too.
Feeding your cat after she has given birth
Once the kittens have been delivered, your cat will immediately begin to nurse them and be producing up to a quarter of a liter of milk each day. This has a dramatic effect on her nutritional requirements, which may increase by two or three times.
During nursing, you should feed her "ad lib"—that is, with no restrictions—as she'll need to eat significantly more than usual. Choose a high-quality, high-energy food that contains the right nutrients and fatty acids her body requires for milk production, and make sure to switch back to her regular food near the end of the nursing period.
It's important to maintain contact with your vet and take your cat for regular check-ups to ensure that she and her kittens are healthy. If you're not certain on the best way to feed your pregnant cat, be sure to talk with your vet who will be happy and able to help.