NEW YORK (Reuters Health) - All cesarean sections put women at increased risk of adverse events, including death, according to the World Health Organization's Global Survey on Maternal and Perinatal Health Research Group.

The group urges that cesareans be done only when medically indicated for the mother or the baby.

The article, published online January 12 in The Lancet, reports the third phase of the WHO global survey, which was conducted in 9 Asian countries in 2007 and 2008: Cambodia, China, India, Japan, Nepal, Philippines, Sri Lanka, Thailand, and Vietnam. It covers the outcomes of nearly 108,000 deliveries in 122 hospitals.

Earlier reports have come from Latin American and Africa.

According to first author Dr. Pisake Lumbiganon from Khon Kaen University, Thailand, and associates, the overall rate of cesarean sections was 27.3%, and the rate of operative vaginal delivery was 3.2%. The most common indications for cesarean section were previous c-section, cephalopelvic disproportion, fetal distress, and abnormal presentation.

China had the highest overall rate (46.2%) of cesareans, and by far the highest rate of cesareans without indication (11.7%). The country with the second highest rate of non-indicated cesareans was Vietnam, at 1%.

Compared with spontaneous vaginal deliveries, operative vaginal deliveries were associated with significantly more maternal deaths, with an adjusted odds ratio (OR) of 3.1.

Any operative procedure increased the maternal mortality and morbidity index (defined as blood transfusion, hysterectomy, internal iliac artery ligation, or death or ICU admission) to a greater extent than spontaneous delivery.

Specifically, compared with spontaneous delivery, ORs for the maternal mortality or morbidity index were 2.1 for operative vaginal delivery, 2.7 for antepartum cesarean without indications, 10.6 for antepartum cesarean with indications, 14.2 for intrapartum cesarean without indications, and 14.5 for intrapartum cesarean with indications.

For neonates, the risk of mortality was significantly increased with operative vaginal delivery (OR 1.6) and intrapartum cesarean with indications (OR 1.5), but decreased with antepartum cesarean without indications (OR 0.3).

For breech and other abnormal presentations, cesarean section - either antepartum or intrapartum -- significantly reduced the risk of perinatal mortality but raised the risk of an extended stay in the neonatal ICU.

The perinatal mortality and morbidity index (defined as death or neonatal ICU stay of 7 days or more) was significantly higher with operative vaginal delivery (OR 1.9), antepartum cesarean with indication (OR 1.9), and intrapartum caesarean with indication (OR 2.1).

Dr. Lumbiganon and associates maintain that "the most important finding of the survey is the increased risk of maternal mortality and severe women who undergo caesarean section with no indication." The increased risk is primarily due to higher rates of ICU admission and blood transfusion.

"If this operation is limited to medical indications and unnecessary use is avoided, resources will be used for a need and will not be taken from other parts of the health system," the authors write.

In a commentary, Dr. Yap-Seng Chon and Dr. Kenneth Y. C. Kwek from the National University of Singapore suggest that "investment in training and clearer guidelines for vaginal birth after cesarean section, intrapartum management, fetal monitoring, and external cephalic version could have wider effect."

They continue, "There is little wrong with medical interventions when indicated, but for those who are still inclined to consider cesarean delivery a harmless option, they need to take a cold hard look at the evidence."

Lancet 2010.