Low back pain is very common and often considered a part of normal pregnancy. Because the pain is always attributed to pregnancy, referral to a specialist is often delayed. We describe a young woman who developed low back pain and signs of progressive spinal cord compression at 33 weeks' gestation of her second pregnancy. Magnetic resonance imaging of the thoracic spine showed a collapsed T11 vertebral body and a large paraspinal and intraspinal tumor compressing on the spinal cord from the right. Emergent surgical decompression and removal of the tumor mass was done. Pathological examination revealed metastatic adenocarcinoma and subsequently, a palpable nodule was found in the left breast, which, on biopsy, proved to be an invasive lobular carcinoma.