Although, the elevation of serum tumor markers in pregnancy is usually associated with the physiology of pregnancy itself, we often find the increasing of alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), lactate dehydrogenase (LDH), carbohydrate antigen-125 (CA-125) and carbohydrate antigen 19–9 (CA19-9) in pregnant patients with immature teratoma. The gene discussed is AFP; the disease is neoplasm.