The effect of breast feeding on lung function at 12 and 18 years in a cohort with a family history of allergy

Abstract

Background: Breastfeeding has been proposed to influence the healthy growth of lungs; but mechanisms to explain this effect are yet to be elucidated. Method: Melbourne Atopy Cohort Study, a longitudinal birth cohort, enrolled 620 unborn children with a first degree relative with allergic disease. Data were collected 18 times in the first 2 years to measure duration of exclusive breastfeeding (breastfeeding without any other oral exposures) and total duration of breastfeeding (breastfeeding regardless of other oral exposures). Pre-bronchodilator lung function was assessed at both 12 and 18 years by spirometry, with post-bronchodilator assessment also performed at 18 years. Linear regression and structural equation models were used to investigate the association between breast feeding duration and lung function at 12 and 18 years, and the potential mechanisms for these relationships. Results: The median duration of exclusive breastfeeding was 14 weeks [IQR 2-20], and median duration of total breastfeeding 44 weeks [IQR 16-60]. Duration of exclusive breastfeeding was associated with an increased pre-bronchodilator mid-expiratory flow at both the 12 (9.9 ml per week, 95% CI = -0.3,20.1 n = 364) and 18 year follow-ups (12.9 ml, 95% CI = 1.2,24.7, n = 409). The ratio of Forced expiratory volume-1/Vital capacity at 18 years was also increased (0.1% per week, 95% CI = 0,0.2). There was no association between total duration of breastfeeding and lung function outcomes or exclusive breastfeeding with post-bronchodilator parameters.While breastfeeding was related to increase in height, reduction of body mass index and reduced risk of respiratory tract infections, these associations were relatively weak, and did not appear to fully explain the observed association between breastfeeding and lung function. Conclusion: In children with family history of allergic disease, exclusive breastfeeding should be promoted as it may have beneficial effects on lung function. Reduced risk of respiratory tract infections, adiposity, and increased height associated with breastfeeding do not appear to fully explain these effects.