Unfortunately, PCOS makes your response to ovarian stimulation variable and unpredictable. I don't think it's a matter of becoming resistant to the puregon, just polycystic ovaries being their usual bloody-minded, unpredictable selves. In my first IVF cycle I was on 150IU - no response at all. An increase to 300IU managed to make me hyperstimulate. The second cycle, we started with the higher dose straight away, but dropped it down much faster. I still hyperstimulated, and did so even worse than the first time despite lower doses being used.

BW