The rates of elective primary cesarian deliveries with no clear medical or obstetric indications are rising in many countries, as the risks are believed to be very low. However, few studies have been large enough to identify differences in the rates of severe morbidity associated with low-risk, elective cesarian delivery and planned vaginal delivery among healthy women at term.
Researchers carried out a retrospective population-based cohort study of 2.3 million women in Canada who delivered between 1991 and 2005. Healthy women who had a primary cesarian delivery for breech presentation were considered the “planned cesarian” group and were compared with a similar group who planned to deliver vaginally.
Overall rates of severe morbidity were 27.3 per 1000 deliveries in the planned group for planned cesarian, compared with 9.0 in the group for planned vaginal delivery. The absolute risk increases were low, yet the planned cesarian group had increased postpartum risks of cardiac arrest, wound hematoma, hysterectomy, major infection, anesthetic complications, venous thromboembolism, and hemorrhage requiring hysterectomy. Adjusted odds ratios ranged from 2.1–5.1.
The group for planned cesarian had a longer hospital stay (additional 1.47 days) and a lower risk of hemorrhage requiring blood transfusion. There was no significant difference in the rate of in-hospital maternal death between the 2 groups.
Among the women in the group for planned vaginal delivery, 8.2% had an emergency cesarian section and 13.9% had an instrumental vaginal delivery. Women having an emergency cesarian delivery were more likely to suffer death or serious morbidity than those with vaginal deliveries.
Bottom line
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Although the absolute difference is small, risks of severe maternal morbidity associated with planned cesarean delivery are higher than those with planned vaginal delivery.
Footnotes
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Source: Liu S, Liston RM, Joseph KS, Heaman M, Sauve R, Kramer MS for the Maternal Health Study Group of the Canadian Perinatal Surveillance System. Maternal mortality and severe morbidity associated with low-risk planned cesarean delivery verus planned vaginal delivery at term. CMAJ 2007;176(4):455–60.
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