Your female pets will not be ‘missing out’ on anything from not breeding, they will not be healthier after having babies, there is no benefit to your pet. If you cannot house, afford, or provide medical care to the babies of your pet don’t breed them. If you can’t have adopters ready by the time the babies are old enough to be adopted out, don’t breed. Your female pet will not be losing out on motherhood by being spayed and will face far more significant health complications if you allow her to breed than she ever would from being sterilized and ‘miss out’ on having babies.