Its not fair putting the mother through another pregnancy so soon after this one. Your best bet is to get her spayed so it doesn't happen again. She won't notice they are gone and her condition will be much better for it. The kittens could also have complications due to the mum being so exhausted and you could have 4 stillborns.
Its kinder all around if you get her spayed.
Its kinder all around if you get her spayed.