The word 'placenta' is used for the afterbirth, which carries blood and nutrients from the mother to the baby when it is in the womb. The placenta is normally positioned in the upper portion of the womb. When the placenta is situated in the lower part of the womb, partially or totally obstructing the birth passage, the term placenta previa or low lying placenta is used.
This condition is seen in about 20% of women early in pregnancy (before 20 wks). As pregnancy advances, the afterbirth usually migrates to the upper part of the womb and the chance of the condition persisting at delivery is about 2 - 3%.
In this condition, there may be bleeding - mild to heavy at different stages of pregnancy, usually in the later months. In most cases however, the baby is not affected as the blood lost comes directly from the mother.
There is no way to prevent the condition but early identification by ultrasonography is helpful. The woman is advised to limit her physical activity and avoid intercourse. Iron tablets, injections or blood transfusions are liberally used throughout pregnancy to boost the blood hemoglobin level in the mother. Hospitalization is advised as soon as any bleeding occurs. There are no medicines to stop the bleeding but in many cases it stops on its own.
Delivery by the abdominal route (cesarean section) is indicated when the placenta partially or totally obstructs the birth passage. Heavy bleeding, not responding to conservative treatment, requires a termination of pregnancy. Blood transfusion facilities should be available at the time of delivery.