Asymptomatic diaphragmatic hernias in reproductive-aged women are rare but pose significant morbidity for pregnancy. This is a case of a woman at 29 weeks' gestation with abdominal pain and shortness of breath. Five years prior she had been incidentally diagnosed with a small congenital diaphragmatic hernia of Bochdalek. Following preconception care, she opted against repair of the hernia prior to pregnancy due to lack of symptoms and no clear recommendation for repair from the surgeon. Imaging studies on emergency room presentation demonstrated a large herniation of viscera into her chest occupying her entire left chest with slight cardiac displacement. Through a multidisciplinary approach, she was stabilised and eventually delivered at 31 weeks due to worsening pulmonary function. The hernia was repaired postpartum. We recommend repair of any diaphragmatic hernia prior to conception to prevent significant maternal and fetal morbidity or mortality. A multidisciplinary approach allows for planning.