PCOS is the leading cause of infertility in women and involves multiple possible hormonal imbalances. What has been learned about its impact on breastfeeding? We will take a look at the emerging evidence for insulin resistance, along with how the frequent co-morbidities of obesity, hyperandrogenism, and thyroid dysfunction can interrelate and also contribute to lactation problems. The next step explores potential strategies/treatments that are based on underlying etiologies. Note: this overlaps with other hormone talks.