Final answer:
Placenta previa occurs when the placenta covers the cervical opening due to the embryo implanting in the lower uterus, posing risks like antepartum hemorrhage.
Step-by-step explanation:
Placenta previa is indeed characterized by the abnormal placement of the placenta over or near the internal cervical os. This condition occurs when the embryo implants in the lower part of the uterus, and as the fetus grows, the placenta may partially or completely cover the cervix.
It is relatively rare, affecting only about 0.5 percent of pregnancies, but is a significant concern due to its association with antepartum hemorrhage, which is profuse vaginal bleeding occurring after week 24 of pregnancy but before childbirth. The normal location of the placenta is typically in the body of the uterus, away from the cervix, which allows for safer development of the fetus and a lower risk of complications during delivery. The typical placement of the placenta in the uterine body, away from the cervix, supports safer fetal development and diminishes the risk of complications during delivery, underscoring the importance of monitoring and managing placenta previa cases.