Obstetric care for patients with cancer diagnoses during pregnancy is medically and ethically complex, and limited prospective data and national guidelines are available to guide care. Guiding principles for treatment are to optimize maternal outcomes while minimizing neonatal morbidity. Oncologic work- up and management are dependent on the trimester of diagnosis, and are specific to the type, stage, and grade of the oncologic diagnosis. Obstetric care should occur within a multidisciplinary setting, with involvement of maternal fetal medicine, oncologic specialists, and mental health support.