Abstract
Background & Objectives: Little is known about early life risk factors for food allergy in children. We examined the association between perinatal characteristics and future risk of food allergy in offspring.
Methods: This nationwide Swedish cohort study of 1,086,378 children born in Sweden in 2001-2012 used prospectively recorded data from health care registers. Using Cox regression, we estimated hazard ratios (HRs) with 95% confidence intervals (CIs) for the association between perinatal characteristics (e.g. caesarean delivery, preterm birth) and food allergy as defined by diagnoses in the National Patient Register, adjusting for infant sex and maternal factors (age at delivery, country of birth, parity, smoking, body mass index and asthma/pulmonary disease).
Results: During the 13-year follow-up, 26,732 children (2.5%) were diagnosed with food allergy. Food allergy was positively associated with caesarean delivery (HR=1.21; 95%CI=1.18-1.25), large for gestational age (HR=1.15; 95%CI=1.10-1.19) and low 5-minute Apgar score (HR=1.22, 95CI=1.10-1.36) but negatively associated with very preterm birth (<32 weeks of gestation: HR=0.74; 95%CI=0.56-0.98). No association was found between food allergy and moderately preterm birth, low birth weight or small for gestational age. Risk estimates were similar when the outcome was restricted to two records of diagnosed food allergy. In 1,000 children undergoing caesarean delivery, an extra 5 developed food allergy compared with the reference group, suggesting that 17% of food allergy in children born with caesarean delivery can be explained by this exposure (attributable fraction).
Conclusions: Caesarean delivery was associated with increased risk of food allergy, whereas very preterm birth with decreased risk.
