Polycystic ovary syndrome (PCOS) is a common disorder affecting women associated with major adverse health outcomes including subfertility and increased risk for type 2 diabetes. PCOS is a complex genetic trait which arises from a combination of genetic risk and environmental such as obesity. Currently, a conclusive diagnosis of PCOS cannot be made until sexual maturation is complete and the patient develops the characteristic diagnostic features of hyperandrogenism, oligomenorrhea, and/or polycystic ovarian morphology. However, studies in girls with increased risk for PCOS, including daughters of affected women and girls with obesity, have identified early reproductive and metabolic features of the syndrome even prior to the onset of puberty. Investigations into the early origins of PCOS have been limited by small sample size and lack of longitudinal data. The ALSPAC cohort includes critical data needed to investigate PCOS, including maternal reproductive histories, hormone levels, and offspring pubertal development, reproductive hormone levels, and menstrual histories. These proposal seeks to identify early clinical and genetic predictors of PCOS. Data collected in this project will be used for preliminary data in planned future innovative investigations of the early origins of PCOS. This study will propose using a translational approach integrating whole genome sequencing, epigenetic, and metabolomics data available in this cohort with clinical predictors of PCOS. This proposed research will have a sustained and lasting impact on the field as it will inform future efforts toward development of targeted prevention and early treatment approaches in at-risk girls.