BACKGROUND AND PURPOSE:

• Due to the increased rates of both cesarean delivery and childhood allergies, it has been suggested that there may be a causal link
• Liao et al. (Archives of Disease in Childhood, 2020) assessed whether cesarean delivery can predict allergy and impaired lung function

METHODS:

• Population-based cohort study
• Data sources
  • Two prospective Australian infant cohorts with similar protocols, run simultaneously  
    • HealthNuts (born 2006-2010) | Infants enrolled at ages 11 to 15 months | Age 6, children underwent skin prick test for food and areoallergens | Parental questionnaires
    • Longitudinal Study of Australian Children (LSAC, born 2003–2004) | Australia’s only national population-based longitudinal child study 
• Exposure
  • Cesarean delivery
• Study design
  • Data on asthma and eczema were extracted
  • Included children ages 6-7 in the two cohorts
  • Spirometric lung function data came from children ages 11-12 years in the LSAC’s Child Health CheckPoint
• Data analysis
  • Logistic regression was used to estimate associations between delivery mode and current asthma and eczema at 6–7 years
  • Linear regression was used to examine lung function at 11–12 years
  • Models adjusted for potential confounding factors

RESULTS:

• Data from a total of 3135 HealthNuts and 3654 LSAC children were analyzed
  • 32.2% born by cesarean in HealthNuts and 30.9% in LSAC
• There was an association between cesarean and asthma at ages 6 to 7 in HealthNuts
  • Adjusted OR (aOR) 1.25 (95% CI, 1.00 to 1.57)
• This association was not seen LSAC
  • aOR 1.05 (95% CI, 0.86 to 1.28)
• There was no association between cesarean and eczema in either study
  • HealthNuts: aOR 1.09 (95% CI, 0.88 to 1.35)
  • LSAC: aOR 0.89 (95% CI, 0.69 to 1.15)
• There was no association with spirometric lung function parameters at age 11–12 years
• Associations not impacted by
  • Duration of breast feeding
  • Maternal history of asthma/eczema
  • Childcare attendance
  • Number of older siblings
  • Pet exposure

CONCLUSION:

• Odds of parent-reported asthma 25% higher in HealthNuts study but not LSAC
• Authors acknowledge study limitations, including the absence of data related to emergency vs elective cesarean delivery
• The authors state that while there was a small, inconsistent excess of parent-reported asthma in one of the cohorts, the excess in asthma did not appear to be allergic in nature and  

Any true effect of caesarean section on childhood asthma appears likely to be small at most

Learn More – Primary Sources:

No obvious impact of caesarean delivery on childhood allergic outcomes: findings from Australian cohorts

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Does Late Preterm Birth Increase Risk of Asthma?

Fish Oil During Pregnancy: Reduction of Asthma Risk in Offspring? 

Does Timing of Introduction of Allergenic Food Affect Risk of Allergic or Autoimmune Disease in Infants