I'll be killed for this but I think the person who posted about the incompatibility possibly meant Kim and Robbie , not for people with fertility issues.
I have fertility issues and I wouldn't have taken that personally to be honest, we are trying and having recurrent miss carriages but we stick through it.
I do agree with the comment about them not having a pot to piss in between them and now they are bringing another little person into that scenario. Kim is still quite young and I feel she still had plenty time to gave a baby, they should have gotten themselves a roof over their head, a stable income and even Robbie a licence to drive then a baby.