There really is no "safe" way to breed a guinea pig. There are absolutely no guarantees that your pig will have a successful pregnancy, or that the babies will be healthy. There are many genetic factors when you're dealing with pet-quality guinea pigs, and it's impossible to know the parents' genetic history.
Also, do you know that if you breed a roan to roan or roan to dalmatian, you can produce a baby known as a "lethal white"- a pink-eyed white baby with severe birth defects? I question whether it's a good idea to breed your pet, but if you insist on going forward with the project, do consider breeding between six months and a year. The sow's pelvic bones won't "fuse" at a year- that's a myth.
But it is true that, just like a young human woman has a better chance at a healthy pregnancy and baby, so does a young guinea pig. Once the sow has babies, she should be fed alfalfa-based, high quality pellets, and alfalfa hay, as well as her normal ration of greens and veggies. The babies ... more.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.