On average, cats have about four kittens per litter1. Many factors go into this, though, including the size, breed, and health of the mother cat. For instance, healthy cats tend to have more kittens, likely because more fertilized eggs were able to develop completely.
The world’s largest litter of kittens was born in 19702, when a Burmese/Siamese mix had a litter of 19 kittens. Four of the kittens were stillborn, but they were still added to the total. This queen (the name for an unspayed female of breeding age) still holds the world record for the largest litter of kittens. All of the surviving kittens were male except for one, strangely enough.
Most cats will not have litters this big, though, not even close. Multiple factors affect how many kittens the average house cat will have in a litter. But even if everything works out perfectly, the typical cat will never have more than 12 kittens in a litter.
Factors That Affect Cat Litter Sizes
Many factors that affect litter sizes are out of our hands. We can’t change our cat’s genetics, for instance. However, there are some factors that we can control.
- Genetics: There is likely a genetic component to litter sizes. Cats tend to have similar litter sizes as their mothers, provided that there aren’t any other major factors involved. However, the science is a bit unclear on how significant this genetic factor is. There have not been any controlled scientific studies on the matter, making it difficult to make any sure conclusions. Certain breeds do seem to have rather small or rather large litters. Therefore, there is some effect on genetics and litter size. If your cat is pedigreed, you may be able to determine their litter size with some accuracy, as you’ll have access to this genetic factor3. With that said, some argue that litter size isn’t directly related to genetics but to size.
- Size: Big cats usually have big litters3. This isn’t odd by any means. Large dogs tend to have large litters too. Big animals having big litters seem to be an overarching theme for most mammal species. Generally speaking, size is related closely to genetics. Many argue that genetics don’t actually play a role in litter size, but a cat’s size (which is tied to genetics) does. Cat breeds that are bigger often have larger litter sizes than cats that are smaller. For instance, Burmese and Maine Coon cats are both recorded as having slightly larger litters (4.3 kittens per litter4). Longhair and Exotic Shorthair cats only have 2.7 kittens per litter on average.
- Diseases: Certain illnesses can affect a cat’s litter size. Theoretically speaking, the same number of eggs would be released and fertilized even if the cat was sick. However, fewer fetuses would develop correctly and make it to the actual birth. If the fetuses stopped developing early in the cat’s pregnancy, the mother’s body would likely reabsorb them. In these cases, most owners don’t even know that it has occurred. Some kittens can continue to develop while other kittens are absorbed. It is not an all-or-nothing process. It is nearly impossible to know how many kittens your cat actually started with, since fetuses can be absorbed before they are even large enough to show up on an ultrasound. Alternatively, kittens lost later in pregnancy are often miscarried or stillborn. Feline infectious peritonitis, feline panleukopenia virus, and feline distemper all affect unborn kittens’ well-being. These latter two diseases do the most damage and can result in abortions and miscarriages. If the queen is infected late in pregnancy, the kittens’ brain development can be affected.
- Nutrition: Nutrition is also exceedingly important. Breeding females should be eating nutritious kitten food or all-life-stages food. Just like any animal, if the queen isn’t healthy, her kittens likely aren’t going to be healthy either. A cat that is malnourished may be unable to carry all of her kittens to term, which will result in smaller litter sizes. Many of the kittens may also be unable to survive long after birth, especially if the mother’s milk is affected.
- Age: There are some that claim age is related to litter size, though we are unable to find any scientific evidence to back this up. The general claim is that younger and older cats will have smaller litters. Middle-aged cats will often have the largest number of kittens. However, this factor seems to have a lesser effect than the others. A middle-aged, sick queen is not going to have a very big litter, for instance.
Does Litter Size Matter?
In many cases, cat owners often want their cats to have more kittens. After all, who doesn’t want more balls of fluff running around?
However, litter size is important in other ways. For instance, studies have found that certain white blood cell counts are raised in kittens from small litters. Typically, white blood cell counts will be higher when your body is fighting an infection. Based on this knowledge, it is hinted that kittens from smaller litters are more likely to get sick.
The research on this is in its very early stages, though. The study was also conducted on feral-type kittens living in outdoor conditions. Therefore, they are likely to be exposed to more illnesses than your average domestic kittens. Furthermore, the increase in illness could be why there were fewer kittens in that litter, to begin with.
There is a strong correlation between litter size and temperament, though. Kittens need littermates during the first few months of their life to develop properly. In single-kitten litters, these littermates are obviously not available. Research has found that mothers of single-kitten litters often play more with the kitten. Still, the kitten receives less social interaction overall than kittens with littermates. Due to this lack of social behavior, the kittens have increased levels of aggression when they grow older.
Generally speaking, the research appears to suggest that more kittens are often better. This fact is true whether you’re looking at the health of the kittens or their later temperament. However, huge numbers of kittens can be harder for the mother to take care of, as you might imagine. Cats with extremely large litters often need a little help from their owners.
Final Thoughts
The largest litter size ever recorded was a litter of 19 kittens. A Burmese/Siamese mix gave birth to this litter back in 1970, and no cat has had more kittens since then. There are many reports of 15-kitten litters, but none that reach close to 19.
Since this queen was a Burmese, her size likely played a role in this huge litter. However, most Burmese, Maine Coons, and similarly sized cats don’t have anywhere near 19 kittens. In fact, the average is closer to four.
There are many factors that affect how many kittens are in a litter. Size and genetics likely play a role. The queen’s overall health is also important. Proper nutrition helps ensure that all the kittens get what they need to thrive. Illnesses can have a negative impact on litter size—some can even affect the development of the kittens.
In the end, moderately sized litters are often best for cats.
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Featured Image Credit: biggunsband, Shutterstock
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