Breastfeeding in Infancy and Risk of Mortality in Adulthood
by Anne Eglash MD, IBCLC, FABM
Do people live longer if they were breastfed as infants?
The researchers of this week’s study were interested in exploring whether people who were breastfed have a lower risk of all-cause mortality as adults. They report that previous research on this topic failed to find an association, but the studies were small, with less than 4000 participants.
The researchers used data from the UK Biobank, that recruited over 500,000 people in England, Scotland, and Wales between 2006-2010. This study only included BioBank participants who were over 40 years of age and who had known whether they were breastfed or not during infancy.
As you can imagine, there are many other life factors that impact mortality rates, and many of these were controlled for, including ethnicity, sex, smoking, education, BMI, alcohol intake, physical activity, and healthy diet score.
The researchers also conducted a meta-analysis, by pooling the results from this study with previous studies on the association between breastfeeding and mortality.
Among the subjects enrolled with the UK BioBank, 25,581 deaths were recorded over 10 years of follow up. Breastfeeding during infancy was associated with a hazard ratio of 0.95, or a 5% lower risk of all-cause mortality in middle and late adulthood. The authors found similar findings in the meta-analysis.
- Breastfeeding was more protective from death among middle-aged adults than seniors.
- Breastfeeding was most likely to protect adults from death due to cardiovascular disease.
- Breastfeeding was most likely to prevent adults from death due to cancer.
- Breastfeeding was most likely to prevent adults from death due to respiratory diseases such as pneumonia.
See the Answer
Breastfeeding in infancy is associated with a lower risk of mortality among children, but the impact on mortality in middle and late adulthood remains unknown.
To assess the association between breastfeeding in infancy and mortality in middle and late adulthood.
We included 383 627 participants aged 40 to 73 from the UK Biobank (2006 to 2010) and followed up until 2021. Hazard ratios and 95% confidence intervals (CI) for all-cause and cause-specific mortality according to breastfeeding in infancy were estimated with Cox proportional hazards regression models. We further did a meta-analysis including results from our present study and three other cohort studies (PROSPERO; number CRD42022348925).
During a total of 4 732 751 person-years of follow-up, 25 581 deaths were identified. Breastfeeding in infancy was associated with lower risks of mortality in middle and late adulthood, with adjusted hazard ratios (95% confidence interval) of 0.95 (0.93 to 0.98) for all-cause mortality; 0.91 (0.87 to 0.96) for cardiovascular mortality, and 0.94 (0.874 to 0.999) for respiratory mortality. Specifically, the association with mortality seemed to attenuate with age –– stronger in middle-aged adults than in older adults. A similar association between breastfeeding in infancy and all-cause mortality was found in the meta-analysis.
Breastfeeding in infancy is associated with a lower risk of mortality –– even decades later –– in middle and late adulthood.
A history of breastfeeding was more closely associated with a decreased risk of death due to cardiovascular disease than from lung diseases or cancer.
This makes sense, as we have plenty of evidence that breastfeeding is associated with more favorable metabolic programming, decreasing the risk of high blood pressure, high cholesterol and obesity among adults who were breastfed.
The strength of association between breastfeeding and risk of death in this large study may have been even greater if they had been able to measure duration of breastfeeding.
Just a tidbit for history- the participants were born between 1934-1970. The ‘any’ breastfeeding rate was nearly 85% in 1934, but declined to just above 60% in the 1960’s.