Breastfeeding and cardiovascular mortality: the Boyd Orr cohort and a systematic review with meta-analysis.
OBJECTIVE
To investigate the association of breastfeeding with all-cause, cardiovascular, and ischaemic heart disease mortality.


RESULTS
A long-term follow-up of 4999 children originally surveyed from 1937 to 1939 was undertaken (Boyd Orr cohort). Four thousand three hundred and seventy-nine subjects (88%) were traced in adulthood and 3555 (71%) had complete data on all covariates. The results were combined with a meta-analysis of the published literature. In the Boyd Orr study, there was little evidence that breastfeeding was associated with all-cause (hazard ratio: 1.04 [95% CI: 0.90-1.20]), cardiovascular (1.04 [0.83-1.30]), or ischaemic heart disease (1.02 [0.77-1.36]) mortality, compared with bottle-feeding. Meta-analyses of observational studies showed little evidence of an association of breastfeeding with all-cause (pooled rate ratio: 1.01 [95% CI: 0.91-1.13]) or cardiovascular (1.06 [0.94-1.20]) mortality. There was a moderate-to-high degree of between-study heterogeneity for the association between breastfeeding and ischaemic heart disease mortality (I2 value-indicating the degree of between-study variation attributable to heterogeneity-66%), and estimates were consistent with both an important beneficial or adverse effect of breastfeeding.


CONCLUSIONS
There is little consistent evidence that breastfeeding influences subsequent all-cause or cardiovascular disease mortality. Results from other well-designed cohorts may clarify residual uncertainty.
Martin
Richard M
RM
Department of Social Medicine, University of Bristol, Canynge Hall, Whiteladies Road, Bristol, Avon BS8 2PR, UK. richard.martin@bristol.ac.uk
Davey Smith
George
G
Mangtani
Punam
P
Tilling
Kate
K
Frankel
Stephen
S
Gunnell
David
D
D001942:Breast Feeding; D002318:Cardiovascular Diseases / Q000401:mortality*; D002423:Cause of Death; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D017202:Myocardial Ischemia / Q000401:mortality; D012423:Rural Health; D014504:Urban Health