The Duration of Neonatal Phototherapy and Allergic Disorders: The Japan Environment and Children's Study.

INTRODUCTION
Currently, the association between the duration of neonatal phototherapy and the risk of allergic disorders has not been reported. This observational cohort study aimed to examine the association between allergic disorders, including food allergies, that are present before 3 years of age and the duration of phototherapy using the nationwide birth cohort data.


METHODS
The Japan Environment and Children's Study was a nationwide birth cohort study. Data of 77,064 infants aged 1 year, 1.5 years, 2 years, and 3 years were analyzed. We divided the participants into three groups: no phototherapy, short phototherapy (1-24 h), and long phototherapy (>24 h) and evaluated the cumulative incidence of allergic disorders before 3 years of age, including asthma, atopic dermatitis, and food allergies. Logistic regression analysis was performed to assess the impact of phototherapy duration on the cumulative incidence of allergic disorders.


RESULTS
After adjustment for potential risk factors, long phototherapy was found to be positively associated with food allergies at age 2 years (OR: 1.16; 95% CI: 1.01-1.33) and all allergic disorders at age 3 years (OR: 1.12; 95% CI: 1.01-1.24), including food allergies (OR 1.18; 95% CI: 1.04-1.35).


CONCLUSION
A long duration of neonatal phototherapy was positively associated with the risk of allergic disorders, especially food allergies.