Claudia E. Kuehni, M.D., MSc, professor at the Institute of Social and Preventative Medicine at the University of Bern, explains:
"In our cohort of school age children, breastfeeding was associated with modest improvement in forced mid-expiratory flow (FEF50) in our whole group and with improvements in forced vital capacity (FVC) and forced expiratory volume at 1 second (FEV1) only in the children of asthmatic mothers.
In contrast, some earlier studies have suggested that breastfeeding might be harmful in the offspring of mothers with asthma."
The team examined data from a nested sample of 1,458 children from the Leicestershire cohort studies, born in the UK between 1993 and 1997. The researchers evaluated duration of breastfeeding, respiratory symptoms, and other exposures by repeated surveys. At age 12, post-bronchodilator FVC, FEV1, FEF50, skin prick tests and peak expiratory flow rates (PEF) were measured.
The researchers found that FEF50 was considerably higher among children who were breastfed than those who were not breastfed, rising by 0.130 L/sec (P=.048) in children breastfed for four to six months, and 0.164 L/sec (P=.041) in children who were breastfed for over six months.
Among children of asthmatic mothers, the investigators found that these effects were larger, with increases of 0.375 L/sec (P=.015) in children breastfed for four to six months and 0.468 L/sec (P=.009) in children breastfed over 6 months.
Considerable improvements in FEV1 and FVC with breastfeeding were only observed in children of mothers with asthma. Results of these analyses did not alter after the researchers adjusted for respiratory infections in infancy and asthma and atopy in childhood.
Limitations of the study included the use of self-report for determining duration of breastfeeding, infections during infancy, maternal asthma, and a modest response rate of the original cohort for laboratory examinations.
Dr. Kuehni, said:
"We observed modest improvements in lung function in breastfed children in our cohort, including the children of mothers with asthma. Furthermore, our data suggest that rather than acting by reducing respiratory infections, asthma or allergy, breastfeeding might have a direct effect on lung growth. This study supports a strong recommendation for breastfeeding in all children, including those with asthmatic mothers."
Written by Grace Rattue