Between the ages of 5 to 9 months, a kitten goes through puberty, reaches sexual maturity and becomes able to reproduce. A cat has an estrous cycle, in comparison to humans who have a menstrual cycle.
An estrous cycle is made up of physiological events that occur between successive periods of sexual receptivity, called "estrus", and often termed "heat". Each cycle is composed of a follicular phase, where eggs get ready to be released, and a luteal phase, the time after egg release, similar to humans. What is different in animals compared to humans, is that estrus, the time of sexual receptivity, happens before ovulation, (egg release) and female animals give off phermones (attractant hormones) that attract the male to the female for breeding. In humans, no phermones are known, so there is no signal for humans that egg release will happen.
A special part of cat reproduction is that cats are induced ovulators; llamas and alpacas are other induced ovulators. An induced ovulator will breed when "in heat". The act of copulation (breeding) causes hormones to be released from the brain, which causes egg release from the ovary. If a cat is bred 4 times in a day, egg release will happen after breeding. Young cats release fewer eggs than mature cats who have been pregnant before. When more eggs are released, more kittens grow.
If a cat goes into heat (estrus) and is not bred, it does not get pregnant.
A healthy cat that is not bred will go into heat every 19 days.
A cat is usually in "heat" (estrus) for up to six days. Its behavior changes, so the estrus is easy to recognize. Just prior to estrus, a cat becomes very affectionate and is not as hostile to a male cat. During estrus, cats are more vocal, they arch their lower back and present their bottom in the air.
Lordosis Posture of a cat "in heat"
When cats breed, the male cat mounts the female and grabs the back of her neck while breeding. During breeding, the female howls, and the noise is very loud and characteristic of breeding. The neck bite and the breeding send a signal to the brain to release hormones that bring on ovulation (egg release). Then pregnancy can begin.
Pregnancy lasts 64 to 69 days (9+ weeks). When a cat is pregnant, she will be more affectionate and hungry. Ways to tell if a cat is pregnant include feeling that the uterus is bigger about 30 days after breeding or by doing tests such as an ultrasound exam or an X-ray. The mother's nipples will be really pink and large before she is ready to deliver her kittens.
Typically there are 2 to 5 kittens in a litter. Kittens nurse for about 3 to 4 weeks before they are weaned.
The mother can breed and start a pregnancy again while she is nursing her kittens. A young cat can therefore have two litters of kittens before she is one year of age. A cat can continue to have litters until she is 8 years of age. If a cat has litters over and over, as might happen to a wild cat, the cat will weaken, and kittens may not survive.
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Bibliography
1. Understanding Cats Their History, Nature and Behaviour. Robert Tabor. David and Charles Publishers 1997
2. Pathways to pregnancy and parturition. P.L. Senger 2nd edition. Current Conceptions Inc. 2003
3. The Book of the Cat Editors Micheal Wright and Sally Walters. Pan Books 1980.
4. The Cat, Diseases and Clinical Management, 2nd edition. Robert G. Sherting. W. B. Saunders. 1994.
