Case reports suggest placental invasion is on the increase. (Hike in C-Sections may be Responsible).

SARASOTA, FLA. -- Placental invasion is not the most common cause of postpartum hemorrhage, but it is occurring more frequently and it has the highest association with maternal complications resulting from postpartum hemorrhage, according to Dr. Gary A. Dildy III.

Case reports published over the past two decades suggest the incidence of these placental abnormalities is on the rise, most likely as a result of the increased cesarean section rates during that time period. At one institution the incidence nearly doubled from just over 0.02% between 1975 and 1978 to 0.04% between 1985 and 1984, Dr. Dildy said at a perinatal symposium sponsored by Symposia Medicus.

Studies also show that prior C-sections are associated with an increased incidence of placental abnormalities. Placenta previa occurs in less than 1% of women with no prior C-sections. The risk increases substantially as the number of prior C-sections increases. In those with placenta previa and a prior C-section, the incidence of abnormal invasion of the placenta is nearly 50%.

"The good news is that mortality associated with placenta accreta has gone down over the past century," commented Dr. Dildy, who is professor of obstetrics and gynecology at Louisiana State University in New Orleans.

The mortality rate associated with placenta accreta was nearly 40% before 1937, only about 10% by 1955, and close to 0% in the late 1990s.

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