Final answer:
Placenta previa is the condition where the placenta is implanted abnormally low in the uterus and covers the cervix partially or completely, leading to potential complications such as antepartum hemorrhage.
Step-by-step explanation:
The condition in which the placenta is abnormally low in the uterus and partially or completely covers the cervix is known as placenta previa. This occurs when an embryo implants too close to the cervix's internal opening (internal os), commonly in the inferior portion of the uterus. As pregnancy progresses and the fetus grows, the placenta may grow to the point where it can cover the cervix either partially or entirely, posing risks such as antepartum hemorrhage, which is profuse vaginal bleeding after week 24 of pregnancy but before childbirth.