According to the search results, cats can reach sexual maturity and get pregnant as early as four months of age. This means that kittens can have kittens. The gestation period for cats is approximately two months, or 63-65 days. Therefore, a cat can have kittens when they are only six months old. It is important to note that there are no proven health or welfare benefits to a cat having a litter of kittens, and there are many health benefits to neutering, including a big reduction in the risk of getting FIV (the cat version of HIV/AIDS) . The best way to avoid unwanted litters and to protect your cat is to get them neutered at four months of age.