title: Associations of maternal atopic diseases with adverse pregnancy outcomes: a national cohort study.
abstract: BACKGROUND
  Maternal asthma has been associated with adverse pregnancy outcomes. Little is known about the influence of other atopic diseases on pregnancy outcomes. We assessed how various maternal atopic diseases might affect preterm birth, stillbirth, and neonatal death.
  
  
  METHODS
  By linking Norwegian national registries, we acquired information on maternal health, socio-demographic factors, pregnancy, birth, and neonatal outcome on all births in Norway from 1967 to 2003.
  
  
  RESULTS
  A total of 1 974 226 births were included. Of these, 1.8% had a record of maternal asthma, 3.4% of maternal atopic dermatitis, and 0.4% of maternal allergic rhinoconjunctivitis. Overall rates of preterm birth, stillbirth, and neonatal death were 6.0%, 0.6%, and 0.5%, respectively. After adjustments for possible confounders, maternal asthma was associated with increased risk of preterm birth (relative risk (RR), 1.15, [95% confidence interval (CI) 1.10, 1.21]). In contrast, maternal atopic dermatitis was associated with decreased risk of preterm birth (RR 0.90, [95% CI 0.86, 0.93]), stillbirth (RR 0.70, [95% CI 0.62, 0.79]), and neonatal death (RR 0.76, [95% CI 0.65, 0.90]). Similarly, maternal allergic rhinoconjunctivitis was associated with decreased risk of preterm birth (RR 0.84, [95% CI 0.76, 0.94]) and stillbirth (RR 0.40, [95% CI 0.25, 0.66]).
  
  
  CONCLUSIONS
  We confirmed the previously reported association of maternal asthma with increased risk for preterm birth. Unexpectedly, maternal atopic dermatitis and allergic rhinoconjunctivitis were associated with decreased risk of preterm birth and stillbirth. Mechanisms for these protective associations are unclear, and our findings require confirmation in further studies.
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway; Department of Pediatrics, Haukeland University Hospital, Bergen, Norway.
authors.forename: Håvard
authors.initials: H
authors.lastname: Trønnes
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Wilcox
authors.forename: Trond
authors.initials: T
authors.lastname: Markestad
authors.forename: Mette Christophersen
authors.initials: MC
authors.lastname: Tollånes
authors.forename: Rolv Terje
authors.initials: RT
authors.lastname: Lie
authors.forename: Dag
authors.initials: D
authors.lastname: Moster
mesh_terms: D000328:Adult; D001249:Asthma / Q000150:complications / Q000453:epidemiology* / Q000276:immunology; D015331:Cohort Studies; D003233:Conjunctivitis, Allergic / Q000453:epidemiology*; D003876:Dermatitis, Atopic / Q000150:complications / Q000453:epidemiology* / Q000276:immunology; D004522:Educational Status; D005260:Female; D006801:Humans; D007223:Infant; D007226:Infant Mortality / Q000639:trends*; D007231:Infant, Newborn; D015201:Meta-Analysis as Topic; D009664:Norway / Q000453:epidemiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology* / Q000276:immunology; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000453:epidemiology* / Q000276:immunology; D015995:Prevalence; D012042:Registries; D065631:Rhinitis, Allergic / Q000453:epidemiology*; D012306:Risk; D012621:Seasons; D050497:Stillbirth / Q000453:epidemiology*
keywords: Atopy; allergic rhinoconjunctivitis; asthma; atopic dermatitis; hay fever; neonatal death; population register; pregnancy outcome; preterm birth; stillbirth