How did Izzie have her kids?

I’m probably going to sound ignorant but are there any professionals that would know the likelihood that izzie could still have children using her own uterus after all of the harsh treatment she went through just 6 years prior? Or did she use a surrogate to carry the zygotes that her and Alex had? I know it’s something we don’t know specifically for her case but I’m just curious about the potential medical statistics/probabilities. Another case that I could potentially compare it to is when Catherine’s patient that had extreme cancer treatment that was supposed to save her uterus, but the treatment was too severe which caused the uterus became friable and had to be removed.