I'm pretty sure that IVF is expensive and time-consuming even if you *do* get it funded. Added to that, the poor are far more likely have children earlier - delaying childbirth 'till your thirties or forties, an important cause of IVF, is a very middle/upper class deal. I just don't see *how* they could have corrected for socioeconomic status, really. Or, as you mentioned, all the preparation stuff - which is definitely correlated to factors like adult weight.

OTOH, it would be pretty bad science if they hadn't thought about that stuff - shockingly so - so I'd have to read the paper before passing judgement there. I just had a look on Scopus and I can't find it, but then, I have no idea what the search terms should be, so. Any info on author/journal of publication?