title: Unconventional Natural Gas Development and Birth Outcomes in Pennsylvania, USA.
abstract: BACKGROUND
  Unconventional natural gas development has expanded rapidly. In Pennsylvania, the number of producing wells increased from 0 in 2005 to 3,689 in 2013. Few publications have focused on unconventional natural gas development and birth outcomes.
  
  
  METHODS
  We performed a retrospective cohort study using electronic health record data on 9,384 mothers linked to 10,946 neonates in the Geisinger Health System from January 2009 to January 2013. We estimated cumulative exposure to unconventional natural gas development activity with an inverse-distance squared model that incorporated distance to the mother's home; dates and durations of well pad development, drilling, and hydraulic fracturing; and production volume during the pregnancy. We used multilevel linear and logistic regression models to examine associations between activity index quartile and term birth weight, preterm birth, low 5-minute Apgar score and small size for gestational age birth, while controlling for potential confounding variables.
  
  
  RESULTS
  In adjusted models, there was an association between unconventional natural gas development activity and preterm birth that increased across quartiles, with a fourth quartile odds ratio of 1.4 (95% confidence interval = 1.0, 1.9). There were no associations of activity with Apgar score, small for gestational age birth, or term birth weight (after adjustment for year). In a posthoc analysis, there was an association with physician-recorded high-risk pregnancy identified from the problem list (fourth vs. first quartile, 1.3 [95% confidence interval = 1.1, 1.7]).
  
  
  CONCLUSIONS
  Prenatal residential exposure to unconventional natural gas development activity was associated with two pregnancy outcomes, adding to evidence that unconventional natural gas development may impact health.See Video Abstract at http://links.lww.com/EDE/B14.
authors.affiliation: From the aDepartment of Environmental Health Sciences, bDepartment of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; cDepartment of Medicine, Johns Hopkins School of Medicine, Baltimore, MD; dDepartment of Epidemiology, Brown University School of Public Health, Providence, RI; eDepartment of Obstetrics and Gynecology, Alpert School of Medicine, Brown University, Providence, RI; fRobert Wood Johnson Foundation Health and Society Scholars Program, UC San Francisco and UC Berkeley, San Franciso, CA; and gCenter for Health Research, Geisinger Health System, Danville, PA.
authors.forename: Joan A
authors.initials: JA
authors.lastname: Casey
authors.forename: David A
authors.initials: DA
authors.lastname: Savitz
authors.forename: Sara G
authors.initials: SG
authors.lastname: Rasmussen
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Ogburn
authors.forename: Jonathan
authors.initials: J
authors.lastname: Pollak
authors.forename: Dione G
authors.initials: DG
authors.lastname: Mercer
authors.forename: Brian S
authors.initials: BS
authors.lastname: Schwartz
mesh_terms: D001034:Apgar Score; D001724:Birth Weight; D015331:Cohort Studies; D057286:Electronic Health Records; D005260:Female; D006801:Humans; D000067071:Hydraulic Fracking / Q000706:statistics & numerical data*; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D055361:Multilevel Analysis; D059206:Natural Gas; D000066388:Oil and Gas Industry; D010414:Pennsylvania / Q000453:epidemiology; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D018566:Pregnancy, High-Risk; D047928:Premature Birth / Q000453:epidemiology*; D016016:Proportional Hazards Models; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D012189:Retrospective Studies
chemical_list: D059206:Natural Gas