Breastfeeding and lung function at school age: does maternal asthma modify the effect?
BACKGROUND
The evidence for an effect of breastfeeding on lung function is conflicting, in particular whether the effect is modified by maternal asthma.


OBJECTIVE
To explore the association between breastfeeding and school-age lung function.


METHODS
In the Leicestershire Cohort Studies we assessed duration of breastfeeding (not breastfed, ≤3 months, 4-6 months, and >6 months), other exposures, and respiratory symptoms by repeated questionnaires. Post-bronchodilator FVC, FEV(1), peak expiratory flow (PEF), forced midexpiratory flow (FEF(50)), and skin prick tests were measured at age 12 years. We performed multivariable linear regression and tested potential causal pathways (N = 1,458).


RESULTS
In the entire sample, FEF(50) was higher by 130 and 164 ml in children breastfed for 4 to 6 months and longer than 6 months, respectively, compared with those not breastfed (P = 0.048 and 0.041), with larger effects if the mother had asthma. FVC and FEV(1) were associated with breastfeeding only in children of mothers with asthma (P for interaction, 0.018 and 0.008): FVC was increased by 123 and 164 ml for those breastfed 4 to 6 months or longer than 6 months, respectively (P = 0.177 and 0.040) and FEV(1) was increased by 148 and 167 ml, respectively (P = 0.050 and 0.016). Results were unchanged after adjustment for respiratory infections in infancy and asthma and atopy in the child.


CONCLUSIONS
In this cohort, breastfeeding for more than 4 months was associated with increased FEF(50) and, in children of mothers with asthma, with increased FEV(1) and FVC. It seems that the effect is not mediated via avoidance of early infections or atopy but rather through a direct effect on lung growth.
Institute of Social and Preventive Medicine, University of Bern, Switzerland.
Cristian M
CM
Dogaru
Marie-Pierre F
MP
Strippoli
Ben D
BD
Spycher
Urs
U
Frey
Caroline S
CS
Beardsmore
Michael
M
Silverman
Claudia E
CE
Kuehni
D000367:Age Factors; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology; D001942:Breast Feeding / Q000379:methods / Q000706:statistics & numerical data*; D002648:Child; D002657:Child Development / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008429:Maternal Welfare; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D012129:Respiratory Function Tests; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014797:Vital Capacity / Q000502:physiology*