The initial care of newborn infants and subsequent hay fever

Background: Patterns of neonatal exposure to microorganisms have changed su bstantially over the last 100 years, and it has been suggested that this ha s influenced the risk of immune-mediated disease. Using a proxy measure, we tested the hypothesis that the initial handling of newborn infants, which is known to affect the pattern of exposure to microorganisms, may alter the risk of developing subsequent atopy, as indicated by hay fever. Methods: Analysis was performed on 5519 members of the 1970 British Cohort Study, a nationally representative birth cohort. Cohort members with hay fe ver were identified at intervals up to the age of 26 years. Details of neon atal care and childhood circumstances were recorded prospectively. Those wh o had spent their first night away from their mother in the communal infant nursery were selected as likely to have experienced atypical exposure comp ared with infants who remained with their mother. Adjustment was made for p otential confounding factors in infancy and childhood by multiple logistic regression analysis. Results: Unadjusted relative odds (with 95% CI) for developing hay fever am ong those spending the first night in the communal nursery, when compared w ith other infants who remained with the mother, were 1.48 (1.23-1.77), P < 0.001. Comprehensive adjustment for the potential confounding factors, incl uding feeding practices on the first day of life, markers of social and mat erial circumstances, and region, did not substantially alter this relations hip, with adjusted relative odds of 1.31 (1.08-1.59), P = 0.005. Conclusions: While our proxy measure is associated with an increased risk o f hay fever, further research is required to confirm that this is due to th e pattern of infectious exposure in very early life. The results are consis tent with the hypothesis that the first challenges are particularly importa nt in the development of the newborn infant's immune system.