From C-section to health conditions: Are Children's Health Outcomes Influenced by Birth Delivery Methods?

C-section rates have risen steadily across the OECD in the past two decades. In the United States and in Canada, they have reached levels nearly twice as high as the benchmark suggested by the World Health Organization. Among the potential consequences of this trend, the impact of C-section birth on health outcomes in childhood has attracted the attention of both the media and the scientific community. Research conducted in clinical settings suggests that a caesarean birth would affect the composition of an infant's intestinal microbiota in his first days of life, with the potential impact of impeding the development of his immune system. However, studies using observational data to investigate the relationship between C-section birth and health outcomes later in childhood offer mixed findings, some confirming and others casting doubts on the association between both phenomena (Bager et al [2008], Biasucci et al[2010]). Overall, more evidence is needed to understand the health repercussions of birth delivery methods on children.

In this paper, I use individual-level data on Canadian infants born between 1994 and 2006, whom I follow from pregnancy through childhood, to investigate the causal impact of C-sections on health outcomes later in life (chronic conditions such as diabetes, asthma and allergies, minor ailments, regular medication use, hospital visits and inpatient stays for a disease/infection, etc.). In addition to controlling for a rich set of observed parental and household characteristics, I account for the endogeneity between health and birth delivery method using an instrumental variables approach that exploits physicians' responsesto financial incentives. Building on Allin, Baker, Isabelle and Stabile [2015], I use the relative payment received by physicians for a C-section, which varies exogenously across Canadian provinces and through time, to instrument for the probability that a newborn is delivered by C-section. The Canadian context, with its universal coverage and single payer health care system, ensures that the parameters considered in the first stage apply to the population of physicians and births in the country.

The identification strategy I use yields a local average treatment effect that corresponds to the impact of an unnecessary C-section on a child's propensity to develop a wide range of health problems. From a public policy perspective, this estimate is particularly interesting: the long-term consequences of unnecessary C-sections being weighted against weaker and disputed short-term benefits. The results will improve our understanding of the long-run costs associated with C-sections births, beyond the cost of the birth delivery procedure itself.

References:

Allin, Sara, Michael Baker, Maripier Isabelle and Mark Stabile (2015), Physician Incentives and the Rise in C-section: Evidence from Canada, National Bureau of Economic Research, Working Paper No 21022.

Bager P, J. Wohlfart and T. Westergaard (2008), Caesarean Delivery and Risk of Atopy and Allergic Disease: Meta-Analyses, Clinical and Experimental Allergy, 38 (4).

Biasucci, Giacomo, Monica Rubini, Sara Riboni, Lorenzo Morelli, Elena Bessi and Cristiana Retetangos [2010], "Mode of Delivery Affects the Bacterial Community in the Newborn Gut", Early Human Development, 86 (1), pp. 13-15.