How long are cats pregnant?
Feline estrous cycle
Cats are seasonally polyestrous, which means they cycle continuously through part of the year, from early spring through late fall, and do not cycle at all for the remainder of the year. Cats can have multiple litters per year. They are also induced ovulators, meaning they do not ovulate until they undergo the physical act of mating, whereas most animals spontaneously ovulate, or release mature eggs. Unfortunately, this causes cats to repeatedly go into heat every two to three weeks throughout the breeding season until they mate, or are spayed. If you do not plan on breeding your cat, she should be spayed when she is approximately 4 months old to prevent unwanted heat-related behaviors and overpopulation.
Like dogs, cats are multiparous, which means they give birth to multiple offspring with each pregnancy. Cats have a Y-shaped uterus with two uterine horns that converge into a single uterine body that serves as the birth canal. Fetuses develop in the uterine horns, and will pass through the uterine body during queening, or the birth process.
Feline pregnancy stages
Feline pregnancy can be divided into three trimesters, or equal periods of approximately 21 days. During each trimester, fetal kittens undergo significant development toward becoming full-term kittens who are ready for entry into the world.
- First trimester — Pregnancy begins when sperm fertilize mature eggs. During mating, the male deposits sperm into the female’s reproductive tract, and the determined cells travel to the oviducts located at the tips of the uterine horns. There, sperm wait for the ovaries to release mature eggs, and a single sperm will fertilize each egg. The single-celled embryos are then swept down into the uterine horns, where they will implant, or attach to, the uterine lining. Several tissue layers will develop around each embryo to form its placenta. Toward the end of the first trimester, different tissues and organs begin to form, although each kitten is still less than one inch long.
- Second trimester — During weeks four through six, individual structures and organs continue to differentiate and develop. The kidneys, liver, and brain become distinct and grow, as does each kitten’s skeletal system. Legs and paws develop, and fetuses take on the characteristic shape of kittens.
- Third trimester — During the third trimester, final fetal details, such as claws and fur, develop. Most importantly, the final three weeks are a period of rapid growth.
During your cat’s first trimester, you probably will not notice any obvious changes. Weight gain will be minimal, and she can continue eating her normal diet.
Weight gain will become more obvious during your cat’s second trimester, and her appetite will likely increase. You should change your cat’s diet to a high-quality kitten food to increase calorie consumption, and allow her to eat as much as she likes.
Your cat will gain considerable weight during the third trimester as her kittens grow, and you will likely see fetal movement as you watch her expanding abdomen. Toward the end of pregnancy, you may notice mammary enlargement as lactation begins. Your cat may also lose hair around her nipples and on her ventral abdomen in preparation for birth.
Feline pregnancy diagnosis
Whether you have intentionally bred your cat, or a stray with a large belly arrived at your door, your family veterinarian can confirm pregnancy using a number of techniques, including:
- Palpation — After approximately three weeks, your veterinarian may be able to gently palpate, or feel, developing kittens in your cat’s uterine horns. This should only be done by a veterinarian’s practiced hands, as too much pressure can easily harm or kill fetuses.
- Ultrasound — After approximately 24 days, your veterinarian can visualize fetal kittens with an ultrasound, which shows real-time movement on a monitor. Each kitten’s heartbeat can be observed to confirm it is viable.
- X-rays — A fetal kitten’s skeleton mineralizes around 42 days of pregnancy, at which time bones become visible on an X-ray. Your cat’s entire abdomen can be captured on an X-ray, which allows your veterinarian to count the number of kittens. Knowing how many kittens to expect is important to ensure your cat delivers her entire litter and no kittens are left in her uterus.
Recognizing queening signs
Your cat will probably not need your help delivering her kittens, but knowing when she will deliver, or queen, is important. If you monitor her physical and behavioral changes, your cat will let you know when she is preparing to give birth, so you can also get ready. Cues to watch for include:
- Nesting — As her delivery date approaches, your cat will start looking for a safe, comfortable place to give birth. To prevent her from using your closet or a hidden spot in the attic—although she may still do this—set up a birthing box by lining a box or basket with layers of blankets or other absorbent material. Your cat will spend more time in the birthing box, or her own pre-determined spot, in the days leading up to queening.
- Appetite changes — Cats commonly eat less, or stop eating altogether, the last few days of pregnancy. If you notice a significant decrease in your cat’s appetite, she likely will give birth soon.
- Body temperature changes — Feline body temperature often decreases one to two degrees fahrenheit shortly before queening. If your cat allows, take her axillary temperature daily by tucking a digital thermometer into her armpit area. If you start taking her body temperature at least a week before her projected due date, you will become familiar with her normal temperature, and recognize a sudden change. A drop in body temperature usually indicates a cat will queen in the next 24 hours.
Delivery of kittens
Cats rarely have difficulty giving birth, and your cat likely will not need your help. You should give her space, and avoid crowding or making her nervous, but remain close by, and observe the process in case your help is needed. Kittens are typically born 15 to 30 minutes apart, and may be born with membranes surrounding them, which your cat should remove. If they fail to do so, you may need to help with this step. Make sure you are in close contact with your trusted veterinarian along the way.