Purpose <p>Approximately 19% of breast cancer cases in 2020 were diagnosed in women under age 50. These premenopausal women with early-stage breast cancer face unique challenges related to family building. This study examines the decision-making and outcomes of patients who pursue fertility preservation before treatment and family building afterwards.</p> Methods <p>Breast cancer survivors seen by a fertility nurse specialist before initiating cancer treatment at Memorial Sloan Kettering Cancer Center (MSKCC) between 2009 and 2017 were contacted to participate. Participants completed a web-based cross-sectional survey examining decisions made about fertility preservation, factors influencing them, and post-treatment reflections and outcomes.</p> Results <p>Prior to treatment, 168 women met with a reproductive endocrinologist and 116 underwent fertility preservation. After completing cancer treatment, 36 women had children and 15 of these women used eggs/embryos frozen prior to treatment. The majority of women deemed these factors “very important” when deciding whether to freeze eggs/embryos: a desire to have a biologic child, the ability to feel hopeful about their future, the chance of success, feeling overwhelmed by their diagnosis, and concerns about having regret if they didn’t freeze their eggs/embryo.</p> Conclusions <p>Over half of patients who attempted family building after treatment were able to have children. Many of these women used eggs/embryos frozen before treatment either by getting pregnant themselves or via surrogacy.</p> Implications for Cancer Survivors <p>This data stresses the importance of referring cancer patients early to a reproductive endocrinologist before initiation of systemic therapy and has high translational promise in the clinical care of all young female cancer survivors interested in fertility preservation.</p>