The risk of mammary cancer is reduced if a cat is spayed before its first heat. Also spayed pets cannot develop pyometra, a serious uterine infection. Finally, difficult pregnancy and delivery in older cats or ill cats is prevented. Your cat will not gain weight, if you provide a balanced diet and encourage regular exercise. Your cat does not need to have a litter of kittens to mature.
Neutering is the primary method of sterilizing male cats.
Neutering an immature cat usually prevents development of mating behavior and the obnoxious habit of spraying urine to mark territory around the house and yard. An unneutered cat cannot control its mating instincts. Given freedom to wander, such an animal may become hurt or lost, and is almost certain to be responsible for unwanted litters. Countless others are abandoned. Discuss your questions about breeding and birth control with your veterinarian.