Countries with a cesarean delivery rate as high as 19% have lower maternal and neonatal mortality, compared with countries that have higher c-section rates, according to a report published online Dec. 1 in JAMA.
The findings suggest that the current World Health Organization (WHO) recommendation that national rates of cesarean delivery shouldn’t exceed 10%-15% of live births may be setting the target rate too low, according to Dr. George Molina of Ariadne Labs at Brigham and Women’s Hospital and the Harvard T.H. Chan School of Public Health, Boston, and his associates.
“The WHO recommendation that population level cesarean delivery rates should not exceed 10%-15% was a consensus opinion based on the observation that some countries with the lowest perinatal mortality rates had cesarean delivery rates that were less than 10/100 live births,” the researchers wrote. “Prior studies suggesting that lower cesarean delivery rate thresholds were optimal for maternal and neonatal mortality were incomplete because they examined data from limited sets of countries and often examined outcomes in wealthier countries.”
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The researchers estimated that globally, the number of cesarean deliveries was 22.9 million in 2012 for a global cesarean delivery rate of 19.4/100 live births.
Cesarean delivery rates of up to 19.1/100 live births were inversely correlated with the maternal mortality ratio at the country level, and cesarean delivery rates of up to 19.4/100 live births were inversely correlated with the neonatal mortality ratio.
Dr. Molina and his colleagues analyzed the most recent information concerning modes of delivery, per capita health expenditures, life expectancy, and numerous other related factors using several multinational health databases. The goal was to estimate national rates of cesarean delivery and relate those figures to maternal and neonatal mortality for as many countries as possible, focusing on the most recent single year (2012) for which adequate data were available.
A sensitivity analysis of the 76 countries with the highest-quality cesarean delivery rate information showed that cesarean delivery rates greater than 6.9 to 20.1 per 100 live births were inversely correlated with the maternal mortality ratio. Cesarean delivery rates of 12.6 to 24.0 per 100 live births were inversely correlated with neonatal mortality (JAMA. 2015 Dec 1;314[21]:2263-70. doi: 10.1001/jama.2015.15553).
The researchers noted that they focused solely on mortality and did not assess other health outcomes. This means that they could not address the many possible benefits of cesarean delivery, such as reduced morbidity from complicated vaginal delivery or from prolonged obstructed labor.
In a separate report, a different research group found that children born by planned cesarean delivery, as compared with vaginal delivery, had a slightly increased risk of asthma requiring hospital admission, of needing a prescription for a salbutamol inhaler at age 5 years, and of all-cause mortality by age 21 years.
Dr. Mairead Blackof the University of Aberdeen (England) and her associates examined the relationship between planned cesarean delivery and chronic illness and death among the offspring. They assessed outcomes in 321,287 singleton live births to first-time mothers that occurred in Scotland in 1993-2007; the children were followed until January 2015, for a mean follow-up of 14.8 years.
In this cohort, 12,355 children (3.8%) were born by planned cesarean delivery, 56,015 (17.5%) by unscheduled cesarean, and 252,917 (78.7%) by vaginal delivery.
Children born by planned C-sections were slightly, but significantly more likely than were those born vaginally to develop asthma requiring hospital admission (3.73% vs. 3.41%; hazard ratio, 1.22).
Compared with children delivered vaginally, those delivered by planned cesarean section also were slightly, but significantly more likely to require a prescription for a salbutamol inhaler at age 5 years (10.34% vs. 9.62%; HR, 1.13) and to die before the age of 21 years(0.40% vs. 0.32%; HR, 1.41).
However, there were no significant differences between the two study groups in risk of developing inflammatory bowel disease (0.11% vs. 0.13%) or cancer (0.23% vs 0.21%), they noted (JAMA. 2015 Dec 1;314[21]:2271-9. doi: 10.1001/jama.2015.16176).
These findings “suggest that avoidance of vaginal birth may be an important early-life factor in the growing global burden of asthma, although absolute increase in risk to individuals is low,” Dr. Black and her associates wrote.
The researchers in both studies reported having no relevant financial disclosures. Dr. Black’s study was supported in part by the Wellcome Trust.