Pregnancy-onset inflammatory bowel disease (POIBD) is a rare diagnosis that has been associated with diagnostic delay and increased risk of hospitalization compared with inflammatory bowel disease diagnosed outside of pregnancy. There is a paucity of data on the clinical presentation and risk factors associated with maternal and fetal outcomes of POIBD. We present a 29-year-old patient who presented with acute severe ulcerative colitis at 24 weeks gestational age whose course was complicated by delayed diagnosis and therapy, colonic perforation, colectomy, prolonged hospitalization, and neonatal prematurity. The case illustrates the high index for suspicion required for making this diagnosis and the prevention of maternal and neonatal morbidity, together with a growing need to advocate for timely investigations and in-patient management in unwell pregnant patients.