You may not have to deal with this if you got your rabbit from a shelter. Most shelters alter their rabbits. But if you bought your rabbit from a pet store, or a breeder of any size, it will not be spayed.
This is one thing that keeps the price down on rabbits is that they breed like rabbits. And that they aren't spayed before you get them. For the most part, you will be buying a rabbit too young to be spayed, because they must be at least four months old to spay.
But it's essential to spay your female rabbit. Whole females are susceptable to cancers of the reproductive organs, which will shorten their lives significantly. They also make for calmer, and happier pets without the urges of reproduction. The phrase "they'll be calmer and live longer" could apply directly to the rabbit.
Female rabbits, once spayed, can also have companions in other altered rabbits. Without altering, the rabbits tend to get too agressive to the same sex, and will, of course, breed with the opposet sex.
Rabbits are also prey animals. They breed much more frequently than ferrets, and small house breeders are a large cause of rabbit overpopulation.
Rabbit spaying is safe when done by a vet experienced in the procedure.
"I'm not going to breed her, or keep her with other rabbits. Why bother?"
Besides the problems of agression and overpopulation, whole female rabbits are susceptable to cancers of the reproduction organs. This can and will shorten her life. Female rabbits have also been found to train more easily and more consistantly when spayed.
"She's so cute. I really want to breed her."
Rabbits are a prey species. They won't just produce one litter, but litter after litter of bunnies, causeing severe stress on the female, and a quick overpopulation of rabbits. How fast do they breed? Within 24 hours of the birth of her litter, a female who is mated by a male may become pregnant again.
Like the ferret, rabbits can have any number of problems when pregnant or having a litter. She may not care for her young for any number of reasons, she may die in delivery, she may become sick from stress.
And what do you do with all the babies? This isn't usually 1 or 2, this can be up to a dozen.
The most important thing to consider is there are too many rabbits because people thought their rabbit was cute and wanted to breed her. There are usually dozens of rabbits in any city shelter, and even more in breed rescues. An untold number of unwanted rabbits are released in the wild each year.
Even one litter is too much. Don't breed. Period.