After failed first IVF I have been recommend metformin. I was recently diagnosed with pcos (none of the usual symptoms). Anyway my question is has anyone any experience of metformin? I've been told I can take prior to next round of IVF and carry on or just when we are starting the cycle. Is there any pros or cons and is it better to start a few cycles before IVF to get used to it? Is it more effective if already been using?