We hypothesize that ovarian aging, as reflected by antral follicle count, is largely determined by common genetic polymorphisms that impact the initial oocyte endowment and/or the rate of oocyte loss over time thus lowering antral follicle count for any given age. We further hypothesize that antral follicle count will be an improved marker of ovarian aging. Thus, we propose a study of the genetic and environmental factors that influence age-specific variability in antral follicle count.