title: Forceps birth delivery, allergic sensitisation and asthma: a population-based cohort study.
abstract: BACKGROUND
  Studies indicate an increased risk of allergies among children born by caesarean section, possibly because immune development is altered by avoiding exposure to maternal vaginal flora. It is unknown if other obstetric interventions are associated with allergies.
  
  
  OBJECTIVE
  To assess associations between delivery with forceps assistance and development of atopy and asthma.
  
  
  METHODS
  In a population-based cohort of 1037 individuals born in 1972/73, atopy was assessed by skin-prick tests for common allergens at ages 13 and 32 years. A history of asthma was obtained at the same ages. Associations between birth with forceps assistance, atopy and asthma were assessed with adjustments for sex, head circumference at birth, parental atopy disease, birth order and socio-economic status.
  
  
  RESULTS
  Children born using forceps were more likely to have atopy at ages 13 (53% vs. 44%) and 32 (68% vs 59%). They were also more likely to have asthma (21% vs. 11% and 23% vs. 16% at ages 13 and 32 respectively). Except for asthma at age 13, these associations were not statistically significant after adjustment for multiple confounding factors.
  
  
  CONCLUSIONS
  Delivery with forceps assistance is associated with an increased risk of atopy and asthma, but the associations were weaker after adjustment for confounding factors. The previously reported association between caesarean birth and atopic disease may be due to confounding rather than altered exposure to maternal flora, although other factors associated with a difficult labour cannot be ruled out.
authors: Department of Preventive & Social Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand. bob.hancox@otago.ac.nz
authors: R J
authors: RJ
authors: Hancox
authors: C E
authors: CE
authors: Landhuis
authors: M R
authors: MR
authors: Sears
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D036861:Delivery, Obstetric; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology / Q000209:etiology; D007114:Immunization; D011159:Population Surveillance; D015995:Prevalence
chemical_list: D000485:Allergens