Early in pregnancy, the zygote (fertilized egg) implants in the uterus and forms a placenta. Implantation that occurs low in the uterus may result in a placenta that is close to or covers the cervical os (birth canal). Most low-lying placentas migrate (move) during later pregnancy towards the fundus (top of the uterus) and away from the cervix.

A low placenta has four degrees of severity:

1. Low-lying placenta: The placenta is implanted low in the uterus close to the cervix but the edge of the placenta does not reach the cervical os.

2. Marginal placenta previa: The edge of the placenta is at the margin of the cervical os.

3. Partial placenta previa: The cervical os is partially covered by the placenta.

4. Total placenta previa: The cervix is completely covered by the placenta.

Women with low-lying placentas generally are not given any restrictions and are followed by periodic ultrasounds. Again, the vast majority of placentas move away from the cervix by the third trimester. However, any bleeding during pregnancy needs to be reported your health care provider right away.

Women diagnosed with placenta previa are often placed on modified bed rest and pelvic rest (no sexual intercourse or orgasm). If the placenta previa persists at term, or if there is heavy bleeding, a cesarean section is needed.

Please discuss your concerns with your health care provider as soon as possible.