INFORMATION FOR WOMEN WHO HAVE PLACENTA PREVIA DURING PREGNANCY

What is placenta previa?

Placenta praevia is a complication of pregnancy in which the placenta – the organ that connects the mother's and baby's blood supplies – develops in the lower section the uterus, thereby covering the cervix, through which a baby must pass during a vaginal delivery. The placenta develops close to where the early embryo has implanted in the wall of the uterus, which normally happens in the upper region of the uterus, called the fundus. However, if the embryo implants lower down, generally the placenta will develop lower down as well. The reasons for this are not clear, but one possibility is that there is a reduction in the number of blood vessels in the fundus, making it a less valuable place for implantation. Some researchers have hypothesized that this can result from previous damage to the fundus, during a spontaneous abortion (miscarriage) or a cesarean section (C-section). Another reason for placenta previa is multiple pregnancy. In most cases of twin and higher pregnancies, each developing baby has its own placenta and there simply is not enough room for all of them to implant in the fundus and for all placentas to attach at the fundus, and so one or more end up attached lower.