You posted a pic of all 4 guinea pigs together including the parents and their first litter ?
http://www.guineapigcages.com/photos...hp?photo=13579
Unless your males are neutered, you shouldn't have them together at all. I noticed you had a roan too. Do you know what lethal whites are?
It really sounds like you are purposefully (and haphazardly) breeding. If so, you should have done your research and you would know the answer to your own question.
There are too many homeless guinea pigs in this state. You don't need to be breeding. Just because your sow had her first litter safely, doesn't mean she will survive the next ones. It's really hard on their bodies.