@article{574748744ba145619a9b72ba234a4db2,
title = "Second trimester sunlight and asthma: Evidence from two independent studies",
abstract = "One in 12 Americans suffers from asthma, and its annual costs are estimated to exceed $50 billion. Yet the root causes of the disease remain unknown. A recent hypothesis posits that maternal vitamin D levels during pregnancy affect the probability the fetus later develops asthma. Employing two large-scale studies, we test this hypothesis using a natural experiment afforded by historical variation in sunlight, a major source of vitamin D. Specifically, holding the birth location and month fixed, we see how exogenous within-location variation in sunlight across birth years affects the probability of asthma onset. We show that this measurement of sunlight correlates with actual exposure, and consistent with preexisting results from the fetal development literature, we find substantial and highly significant evidence in both data sets that increased sunlight during the second trimester lowers the subsequent probability of asthma. Our results suggest policies designed to augment vitamin D levels in pregnant women, the large majority of whomare vitamin D insufficient, could be very cost effective and yield a substantial surplus.",
keywords = "Asthma, Natural experiment, Sunlight, Vitamin D",
author = "Nils Wernerfelt and Slusky, {David J.G.} and Richard Zeckhauser",
note = "Funding Information: We thank Amitabh Chandra and Scott Weiss, MD, two referees, and the editor for detailed comments and suggestions, and conference and seminar participants at the Leonard Davis Institute, Princeton{\textquoteright}s Center for Health and Wellbeing, MIT, UMKC Bloch School, Lafayette College, University of Chicago HEW, NHESG, UIUC, APPAM, and Creighton University. We also thank Bob Krasowski of the Centers for Disease Control, and Jean Roth and the rest of the staff at NBER for outstanding assistance with compiling our data sets, and Diane Alexander, Asaf Bernstein, Hoyt Bleakley, Anne Case, Alma Cohen, Janet Currie, David Cutler, Moshe Hazan, Fernanda Marquez Padilla, Sarah Moshary, Paul Murphy, Stephen Murphy, Joseph Newhouse, Jessica Pickett, Analia Schlosser, Benjamin Sommers, Helena Svaleryd, Laura Wherry, Heidi Williams, and especially Adam Sacarny for valuable comments. Wernerfelt gratefully acknowledges the support of an NSF Graduate Research Fellowship. This paper explores asthma emergency rates in children using outpatient data from Arizona and New Jersey, State Emergency Department Databases (SEDD), Healthcare Cost and Utilization Project (HCUP), and the Agency for Healthcare Research and Quality. The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the Research Data Center, the National Center for Health Statistics, or the Centers for Disease Control and Prevention. Publisher Copyright: {\textcopyright} 2017 American Society of Health Economists and Massachusetts Institute of Technology.",
year = "2017",
month = may,
day = "1",
doi = "10.1162/ajhe_a_00073",
language = "English (US)",
volume = "3",
pages = "227--253",
journal = "American Journal of Health Economics",
issn = "2332-3493",
publisher = "MIT Press Journals",
number = "2",
}
