title: Prenatal exposure to acid-suppressive drugs and the risk of childhood asthma: a population-based Danish cohort study.
abstract: BACKGROUND
  Proton pump inhibitors (PPIs) may activate the immune system and cause asthma.
  
  
  OBJECTIVE
  To investigate the association of prenatal exposure to PPIs and histamine 2-receptor antagonists (H2RAs) with risk of asthma.
  
  
  METHODS
  In this cohort study, 197,060 singletons born between 1996 and 2008 in northern Denmark were followed until the end of 2009. Data were obtained through Danish medical registries. Asthma in offspring was defined as at least two prescriptions of both a β-agonist and an inhaled glucocorticoid and/or a hospital diagnosis of asthma during the follow-up. Cox proportional-hazard regression was used to compute incidence rate ratios, adjusting for covariates.
  
  
  RESULTS
  A total of 2238 (1.1%) children were prenatally exposed to PPIs and 24,506 (12.4%) children developed asthma during follow-up (median follow-up = 6.8 years). The adjusted IRR (aIRR) of asthma associated with prenatal exposure to PPIs was 1.41 (95% confidence interval (CI): 1.27-1.56), compared with those unexposed. The association did not vary by trimester of exposure, and prenatal exposure to H2RAs was associated with similar increase in risk. The aIRR for maternal PPI and H2RA use in the year after, but not during pregnancy was 1.32 (95% CI: 1.20-1.46) and 1.13 (0.93-1.36), respectively, compared with non-use during and in the year after pregnancy.
  
  
  CONCLUSIONS
  Prenatal exposure to both PPIs and H2RAs was associated with an increased risk of asthma in our study. Because the observed association is not drug specific and also observed for maternal postnatal use it may be explained by a 'class effect' or maternal underlying condition.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Denmark. abta@dce.au.dk
authors.forename: A B T
authors.initials: AB
authors.lastname: Andersen
authors.forename: R
authors.initials: R
authors.lastname: Erichsen
authors.forename: D K
authors.initials: DK
authors.lastname: Farkas
authors.forename: F
authors.initials: F
authors.lastname: Mehnert
authors.forename: V
authors.initials: V
authors.lastname: Ehrenstein
authors.forename: H T
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000139:chemically induced* / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005764:Gastroesophageal Reflux / Q000188:drug therapy*; D006635:Histamine H2 Antagonists / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D008297:Male; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced* / Q000453:epidemiology; D054328:Proton Pump Inhibitors / Q000009:adverse effects*; D012044:Regression Analysis; D012307:Risk Factors; D055815:Young Adult
chemical_list: D006635:Histamine H2 Antagonists; D054328:Proton Pump Inhibitors