That is when the veins of the placenta grow too deeply in the uterine wall. It can cause severe hemorrhage at birth. The placenta normally detaches and is delivered following birth. With placenta accreta, the placenta doesn’t detach normally and causes heavy bleeding.
DISCLAIMER: Catholic Answers has turned over the archive to Catholic-Questions.org and no longer owns, manages, or moderates the forums. For additional apologetics resources please visit www.catholic.com.