The effect of breastfeeding duration on lung function at age 10 years: a prospective birth cohort study

Ikechukwu U Ogbuanu ^1*, Wilfried Karmaus ¹, Syed Hasan Arshad ², Ramesh J Kurukulaaratchy ³ and Susan Ewart ⁴

¹ Epidemiology & Biostatistics, University of South Carolina, United States
² David Hide Asthma and Allergy Research Centre, Isle of Wight and University of Southampton, United Kingdom
³ Southampton General Hospital, United Kingdom
⁴ College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States

^* To whom correspondence should be addressed. E-mail: dr_iyke{at}yahoo.com.

Accepted 7 September 2008

Abstract

Introduction: The protective effects of breastfeeding on early life respiratory infections are established, but there have been conflicting reports on protection from asthma in late childhood. We assessed the association of breastfeeding duration and lung function in 10-year olds.

Methods: In the Isle of Wight birth cohort (n=1,456), breastfeeding practices and duration were prospectively assessed at birth and at subsequent follow-up visits (1 and 2 years). Breastfeeding duration was categorized as "not breastfed" (n=196); "<2 months" (n=243); "2 and <4 months" (n=142) and ">=4 months" (n=374). Lung function was measured at age 10 (n=1,033): forced vital capacity (FVC); forced expiratory volume in 1 second (FEV1); FEV1/FVC ratio; and peak expiratory flow (PEF). Maternal history of asthma and allergy were assessed at birth. We analyzed the effect of breastfeeding on lung function using general linear models, adjusting for birthweight, sex, current height and weight, family social status cluster and maternal education.

Results: Compared to those who were not breastfed, FVC was increased by 54.0 +/- 21.1 (SE) ml (p = 0.001); FEV1 by 39.5 +/- 20.1 ml (p=0.05); and PEF by 180.8 +/- 66.1 ml (p=0.006) in children who were breastfed for at least 4 months. In models for FEV1 and PEF that adjusted for FVC, the effect of breastfeeding was retained only for PEF (p=0.04).

Conclusions: Breastfeeding for at least 4 months enhances lung volume in children. The effect on airflow appears to be mediated by lung volume changes. Future studies need to elucidate the mechanisms that drive this phenomenon.