PCO doesn't actually necessarily affect fertility. I think you're thinking of PCOS which is a different thing altogether. Many women suffer from PCO but they don't necessarily suffer from PCOS.

About 25% of women have ovaries that can be diagnosed as polycystic on ultrasound. This is called PCO and it can occur for a number of reasons.

Women with polycystic ovaries (PCO) do not necessarily have the syndrome (PCOS).

In PCOS the so-called cysts are actually small follicles that have not matured to release an egg.