A highly-digestible, high quality kitten/growth/development formulation is generally recommended during feline pregnancy. The best options are those diets that have passed feeding trials for gestation/lactation or for all life stages.
Is milk good for pregnant cats?
At the beginning of her pregnancy, you should feed your queen a fat-rich diet, specifically designed to support gestation and, later, the production of milk to feed her kittens. Switch her onto this food progressively by mixing it with her existing food, starting with 25% new food and 75% existing food.
Should I feed my pregnant cat kitten food?
A high-quality kitten food will provide all the necessary nutrients when feeding your pregnant cat. Start weaning her onto it from mating until a few weeks after giving birth, to keep her strong and give her the energy she needs to support her new kittens.