During pregnancy, the
placenta is normally attached to the upper wall of the
uterus. A placenta that forms low in the uterus
without overlapping the
cervical opening is referred to as a low-lying
placenta. It is not a high-risk condition. It often gets better on its own
as the pregnancy progresses.
If you have a low-lying placenta early in pregnancy, there is a good
chance that it will get better on its own. As the lower uterus enlarges, the placenta's relative position will
shift away from the cervix.
But when the placenta does overlap the cervix, it
placenta previa. Placenta previa can bleed heavily during labor.
The good news is that about 90% of cases diagnosed before the 20th week
no longer overlap the cervix by the end of the pregnancy.footnote 1
Williams DE, Pridjian G (2011). Obstetrics. In RE Rakel, DP Rakel, eds., Textbook of Family Medicine, 8th ed., pp. 359-401. Philadelphia: Saunders.