These findings, while interesting, couldn’t tell us if being a physician itself caused worse birth outcomes. To help answer that part of the question, we used a “natural experiment” that was designed to improve the working environment for some physicians. Natural experiments are instances in which people are exposed, by chance, to one path or another that allows researchers to study cause and effect (in this case, studying the impact of improved working conditions on health, a question that would be difficult to study in a controlled, randomized study).
In 2011, the Accreditation Council for Graduate Medical Education enacted a reform that limited the number of hours that first-year residents (physicians in training) could consecutively work to be less than 16 consecutive hours. The reform was intended to improve the working conditions for first-year residents.
Since the work reform only affected physicians, we could compare the birth outcomes of physician mothers to those of lawyer mothers before and after the reform to understand how an improvement in working conditions affected physician mothers’ birth outcomes. (Lawyer mothers should be unaffected.) In addition, because the reform was targeted at first-year residents, we focused on physicians who were 26 to 30 years old at the time the reform was enacted.
