title: Maternal bereavement and childhood asthma-analyses in two large samples of Swedish children.
abstract: BACKGROUND
  Prenatal factors such as prenatal psychological stress might influence the development of childhood asthma.
  
  
  RESULTS
  We assessed the association between maternal bereavement shortly before and during pregnancy, as a proxy for prenatal stress, and the risk of childhood asthma in the offspring, based on two samples of children 1-4 (n = 426,334) and 7-12 (n = 493,813) years assembled from the Swedish Medical Birth Register. Exposure was maternal bereavement of a close relative from one year before pregnancy to child birth. Asthma event was defined by a hospital contact for asthma or at least two dispenses of inhaled corticosteroids or montelukast. In the younger sample we calculated hazards ratios (HRs) of a first-ever asthma event using Cox models and in the older sample odds ratio (ORs) of an asthma attack during 12 months using logistic regression. Compared to unexposed boys, exposed boys seemed to have a weakly higher risk of first-ever asthma event at 1-4 years (HR: 1.09; 95% confidence interval [CI]: 0.98, 1.22) as well as an asthma attack during 12 months at 7-12 years (OR: 1.10; 95% CI: 0.96, 1.24). No association was suggested for girls. Boys exposed during the second trimester had a significantly higher risk of asthma event at 1-4 years (HR: 1.55; 95% CI: 1.19, 2.02) and asthma attack at 7-12 years if the bereavement was an older child (OR: 1.58; 95% CI: 1.11, 2.25). The associations tended to be stronger if the bereavement was due to a traumatic death compared to natural death, but the difference was not statistically significant.
  
  
  CONCLUSIONS
  Our results showed some evidence for a positive association between prenatal stress and childhood asthma among boys but not girls.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.forename: Caroline Olgart
authors.initials: CO
authors.lastname: Höglund
authors.forename: Petra
authors.initials: P
authors.lastname: Arck
authors.forename: Cecilia
authors.initials: C
authors.lastname: Lundholm
authors.forename: Niklas
authors.initials: N
authors.lastname: Långström
authors.forename: Paul
authors.initials: P
authors.lastname: Lichtenstein
authors.forename: Mats
authors.initials: M
authors.lastname: Lekander
authors.forename: Catarina
authors.initials: C
authors.lastname: Almqvist
mesh_terms: D001249:Asthma / Q000209:etiology*; D001601:Bereavement; D004198:Disease Susceptibility / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D009035:Mothers / Q000523:psychology; D016017:Odds Ratio; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012737:Sex Factors; D013548:Sweden / Q000453:epidemiology
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