Lack of Relationship between Birth Conditions and Allergic Disorders in Japanese Children Aged 3 Years

Abstract

Background. The current cross-sectional study examined the associations between low birth weight (LBW), preterm birth, and small-for-gestational-age (SGA) and the prevalence of wheeze, asthma, and eczema in Japanese children aged 3 years. Methods. Study subjects were 2004 children. All data were obtained using a questionnaire. Outcomes were defined according to the criteria of the International Study of Asthma and Allergies in Childhood. Adjustment was made for sex, number of siblings, breastfeeding duration, paternal and maternal educational level, paternal and maternal history of allergic disorders, maternal smoking during pregnancy, secondhand smoke exposure at home, and gestational age at birth. Results. The prevalence of wheeze, asthma, and eczema in the previous 12 months were 22.1%, 9.0%, and 17.5%, respectively, and 8.4% were classified as LBW (<2500 g), 4.7% as preterm birth (<37 weeks), and 7.1% as SGA (<10th percentile). There were no significant associations between LBW, preterm birth, or SGA and the prevalence of wheeze, asthma, or eczema. A positive relationship between preterm birth and asthma was of borderline significance in children whose mothers had smoked during pregnancy (adjusted OR: 4.71 [95% CI: 0.97−21.39]), but not in those whose mothers had never smoked during pregnancy; the multiplicative interaction between preterm birth and maternal smoking during pregnancy with respect to asthma was significant (p = .04). Conclusions. The current study failed to detect significant associations between birth conditions and allergic disorders. Nevertheless, we did find evidence for an interaction between preterm birth and maternal smoking during pregnancy affecting asthma.

• asthma
• eczema
• low birth weight
• maternal smoking during pregnancy
• preterm birth
• small-for-gestational-age
• wheeze

Acknowledgments

The authors thank Drs. Masako Sakamoto, Yasuko Arase, and Miki Nagano, the Fukuoka City Government, and Professor Tomoko Shirota of Nakamura Gakuen University, for their valuable support. The authors also thank all the children and parents who participated in this study.

Declaration of Interest

This research was supported by Health and Labour Sciences Research Grants for Research on Allergic Disease and Immunology and Health Research on Children, Youth and Families from the Ministry of Health, Labour and Welfare, Japan.