Has your cat just had kittens? This is a busy and exciting time in your home. While mom is busy taking care of her babies, her body will be going through hormonal changes to prepare for her next heat cycle.
You may have heard that female cats cannot get pregnant as long as they are still nursing kittens. Unfortunately, this not true. Most cats will have an estrus cycle (heat cycle) about 4 weeks after weaning their kittens if it is still the breeding season. She may still be nursing and in heat at the same time.
Estrus is described as the period of receptivity to mating and is linked with the production of estradiol (a type of estrogen) produced by ovarian follicles. It is not to be confused with menstruation in human females, and you will rarely, if ever, see any signs of blood, although occasional mucous discharge may be evident.
When Can Cats Become Pregnant Again?
Female cats are induced ovulators, which means that ovulation does not take place without mating or manual stimulation. If the female cat does not mate during estrus, hormonal levels will eventually drop off, and the estrus cycle will cease until it repeats itself in another two to three weeks. If she does mate, she can easily become pregnant during her first post-birth estrus cycle.
Ovulation will usually occur within 20 to 50 hours after mating, and the eggs are viable (capable of being fertilized) for approximately one day. The eggs are fertilized in the oviduct, and then make their way to the uterus via the uterine horn, implanting in the uterine lining within 10 to 12 days. Cats may mate several times before ovulation is complete and a female cat's litter may end up having kittens from multiple sires. On the street, a female cat in estrus may mate with two or more male cats over the length of the estrus cycle; up to 21 days, with an average of seven days.
Both male and female kittens may reach sexual maturity between four and six months of age, so it is entirely possible a kitten could impregnate his mother. This is potentially dangerous both for female cats and for her kittens. Several repeat pregnancies with only short periods between giving birth can harm a cat's health. Bearing kittens, giving birth, and nursing them can exhaust a cat's physical resources, leaving her malnourished and exhausted.
Responsible breeders of purebred cats keep this in mind and limit the number of litters a given female cat will have, and keep a reasonable gap of time between litters to enable her to completely wean her kittens and to recover her optimum health. At some point the female cat will be retired, at which time she will be spayed, to prevent any further pregnancies, and to allow her to enjoy her senior years, so richly deserved.
If your cat has had kittens and is not a quality breeding cat, it's best to have her spayed after the kitten are weaned. In the meantime, make sure she does not have access to intact males cats or the outdoors.
Reasons for Neutering and Spaying Cats
Unless your cat is a purebred, there is no legitimate reason to allow her to continue having kittens. The reality is that although it has been improved by educating the public on the importance of spaying and neutering pets, there is still a major pet overpopulation problem in the United States.
Since kittens are so popular, the majority of people will end up adopting kittens instead of adult cats. This leaves the adult cats behind without homes and at risk of euthanasia. The more kittens that are available, the greater the risk of euthanasia to adult cats.
Once she's had kittens and had weaned them, it's best to get a female cat spayed. All kittens should be neutered or spayed by the age of four months. Note that kittens can and will mate with their littermates when they become sexually mature. It's best to make sure they are sterilized well before then. It can be very dangerous for young cats to become pregnant.
Spaying or neutering means your cats will be happier and will make better pets in the long run.
Little, Susan E. Female Reproduction. The Cat, 2012, pp. 1195-1227. Elsevier, doi:10.1016/b978-1-4377-0660-4.00040-5
Spaying And Neutering. Cornell University College Of Veterinary Medicine, 2020