The cause is not known. It is likely due to prior injury and scarring of the lining of the womb. This can happen if you have had many pregnancies, a cesarean section (C-section), or prior placenta previa.
Symptoms differ and depend on how much of the cervix is covered. The main sign is painless bleeding from the birth canal. It can range from light to very heavy. It most often happens during late pregnancy. It often happens after sex.
Podrasky AE, Javitt MC, Glanc P, et al. American College of Radiology (ACR) Appropriateness Criteria for second and third trimester bleeding. Available at: ...(Click grey area to select URL) Updated 2013. Accessed June 6, 2016.
Pregnancy complications. Office on Women's Health website. Available at: ...(Click grey area to select URL) Updated June 6, 2018. Accessed August 8, 2018.