Placenta previa is a condition of pregnancy when the placenta implants in the lower part of the uterus, partly or completely obstructing the cervical outlet to the vagina (birth canal).
Review Date 4/19/2022
Updated by: John D. Jacobson, MD, Department of Obstetrics and Gynecology, Loma Linda University School of Medicine, Loma Linda, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.