Cats are funny creatures. Some days the love you, other days they could care less. Well it happens to the best of us, and what you do is resolve to take care of the kittens, find them good homes, and then schedule your kitty for a little elective surgery. As soon as you begin to expect that you have a momma cat, you should gradually switch her over from her regular food to a kitten food.
Kitten food is richer in nutrients and contains more calcium, both important to a pregnant female.
You will also want to provide her with a safe bed, and plenty of clean bedding materials. If she is an inside cat, this should be easy enough. Line a box with clean towels or rags and she will probably make herself right at home. If she is an outside cat, you can attempt to bring her in. If she is resistant and unhappy in the house, you can provide the same type of box for her outside, in a sheltered area.