How long do Maine Coons continue to breed?

This applies to all domestic cats. Maine Coons probably have slightly shorter life spans than moggies. And their health is compromised by inherited diseases which are been well documented. These probably affect their effective breeding lifespan.

But in short, the general answer to the question is a very long time. Male cats have been known to produce offspring at the advanced age of 16 years. This is something like a human being in his 70s.

Maine Coon family. Image copyright Helmi Flick.

Female cats have been known to give birth when 12 years of age. There is a recent story on the Internet about a 30-year-old cat giving birth! That obviously is an exception (unique actually) and the cat was not a Maine Coon. In fact, I can't recall any Maine Coon living to the age of 30. That would be an incredible rarity.

A 12-year-old cat is probably the equivalent of around the mid-60s for a human female. There is a story on the Internet of a woman giving birth at the age of 70. So there seems to be an equivalency between domestic cats and humans in general.

There would be a gradual decline in the number of kittens produced in each litter as a female cat advances in age and her reproductive apparatus begins to slow. It would depend upon the cat as the strongest and healthiest will be more productive later in life.

In general, it's probably fair to say that pedigree cats are not so long lasting because of selective breeding which is inbreeding and inbreeding compromises health as we all know by now.

One website says that female cats should be ready for breeding at around 18-24 months of age. I can't find any information on the topic of breeders and how they handle their queens. In practice, it must be the case that they breed their females for a much shorter time than those I've mentioned in the article above. I suspect they don't talk about it.

In general, the breeding of domestic cats is not very pleasant in my opinion. Often, they are kept in cages even outside because the males are badly behaved in the eyes of people as they are unneutered. The whole breeding process is a little bit unpleasant I would argue but that's my point of view. I would go further than that but I'm going to stop there.