Successful pregnancy requires a well formed egg ( mature follicle ). If there are too many follicles, chances are they are not mature enough, so that won't result in a pregnancy (PCOD) Also, they may all persist, grow to a big size and result in a complication called 'ovarian hyperstimulation syndrome'. Also, More chances of multiple pregnancy (twin, triplet, which is high risk). The size ( maturity) and number of those eggs matters.