There's no doubt cesarean section has advanced modern medicine — neonatal and maternal mortality rates and health have significantly improved since it was introduced. They have in Western cultures, anyway; rates and risks skew higher in Latin American and Asian hospitals. Despite how hard it is to gather an optimal delivery rate, the World Health Organization (WHO) recommends national rates not exceed 10 to 15 C-sections per 100 live births. Skeptical, two new studies published in the Dec. 1 issue of JAMA set out to see if they can provide better estimates for cesarean delivery and health outcomes.

The first study was led by Dr. George Molina, a surgical research resident at Massachusetts General Hospital in Boston. He and his colleagues obtained the most recent cesarean delivery rates in 172 countries, as well as population and health data from a variety of sources. The data included information relevant to mortality rates, life expectancy at birth, percent urban population, total fertility rate, and the national birth rate.

When study authors say neonatal mortality rate, they mean "neonates who die before reaching 28 days of age per 1,000 live births." Maternal mortality, then, refers to "death from pregnancy-related causes while pregnant or up to 42 days postpartum per 100,000 live births."

Based on collected and imputed data, study authors found the optimal cesarean delivery rate could be 19 cesarean delivers per 100 live births. They added the current recommendation at 10-15 is "based on the observation that some countries with the lowest perinatal mortality rates had cesarean delivery rates that were less than 10 per 100 live births."

"The strength of the current study is the use of available data from 172 countries and inclusion of data estimated for a single year, 2012, and cesarean delivery rates for all WHO member states," study authors wrote. "By focusing the estimates to a single year, we avoided possible bias caused by using cesarean delivery rate data from varying years, since cesarean delivery rates and mortality change over time."

What about C-section outcomes? This was the focus of the second JAMA study, led by Mairead Black, a clinical lecturer and research fellow in obstetrics at the University of Aberdeen in the UK. She and her team explored the association between planned C-section and chronic illness (asthma and type 1 diabetes) and death in offspring using a national birth cohort. This cohort identified live births in first-time mothers between Jan. 1, 1993 and Dec. 31, 2007 in Scotland; offspring were followed up until January 2015.

Offspring in this study were compared with offspring born by unscheduled cesarean delivery and with offspring delivered vaginally. Live births were defined as "planned cesarean delivery" if delivery was recorded as "scheduled," with all remaining C-sections recorded as "unscheduled."

Black and her team found "no significant difference in the risk of asthma requiring hospital admission"between scheduled and unscheduled C-section. They did, however, look for a secondary outcome and it was the development of T1D. Results showed offspring born by C-section were more likely to develop this type of diabetes than those born by unscheduled C-section, despite adjusting for maternal type 1 diabetes.

What's more is risk of death up to age 1 was lower following scheduled C-section compared with unscheduled C-section. Taken altogether, first-time mothers' planned C-section was "associated with a small increase in risk of offspring asthma and death in childhood when compared with vaginal birth — but not when compared with unscheduled C-section." These offspring also face "small, but significantly increased risk of type 1 diabetes compared with those born by unscheduled C-section," which, authors admitted, wasn't something they expected to find.

In an accompanying editorial, Drs. Mary E. D’Alton and Mark P Hehir consider the results of each study and write "cesarean delivery rates have long been viewed as a marker of quality, but viewed in isolation they provide inadequate information regarding the quality of practice in a health care system." In which case, they suggest "endeavors to lower the cesarean delivery rate should only be attempted if those efforts bring a clear benefit to patient outcomes."

"The optimal level of cesarean delivery cannot be as simple as a one-fits-all figure to be applied to all institutions and health care systems, and the obstetrical community must accept the fact that 'the appropriate' cesarean delivery rate remains unknown," D'Alton and Hehir concluded. "However, it is not whether the cesarean delivery rate is high or low that really matters, but rather whether appropriate performance of cesarean delivery is part of a system that delivers optimal maternal and neonatal care after consideration of all relevant patient and health system information."

Sources: Molina G et al. Relationship Between Cesarean Delivery Rate and Maternal and Neonatal Mortality. JAMA. 2015.

Black M et al. Planned Cesarean Delivery at Term and Adverse Outcomes in Childhood Health. JAMA. 2015.