The document summarizes evidence from multiple studies on the relationship between breastfeeding and infant infection. Three studies are critically appraised: a prospective cohort study from Hong Kong found exclusive breastfeeding for at least 3 months was associated with lower risk of hospitalization for infection in the first 6 months. A UK retrospective cohort study found exclusive breastfeeding was associated with 30-63% lower risk of lower respiratory tract infections and diarrhea hospitalizations. A systematic review of 15 large cohort studies found a protective relationship between breastfeeding and incidence of diarrhea and pneumonia, with a 40% reduction in gastrointestinal illness risk and 4.91 times higher hospitalization for infants never breastfed. The evidence suggests breastfeeding, particularly exclusive breastfeeding, significantly reduces the risk of

1. • Worldwide, over three million newborns die each year in their
first four weeks of life, with the number one cause of death
being infections
• Up to two thirds of these deaths are preventable with the proper
care during and after birth, including exclusive breastfeeding
• The American Academy of Pediatrics recommends babies
should be breastfed exclusively for the first six months
• In 2014 79% of U.S. new mothers started to breastfeed in 2011,
but only 41% were still exclusively breastfeeding at 3 months
and 18% at 6 months
• Respiratory infections alone, are one of the leading causes of
pediatric hospitalization and outpatient visits in the U.S., with
influenza causing over 200,000 hospitalizations and 36,000
deaths each year
• Infections cost the U.S. over $120 billion each year
• In 2013, Medicaid alone spent over $438 billion on healthcare
Background
• Population. Studies that include full-term newborns from birth
to 1 year of age.
• Intervention. Studies that include breastfeeding or bottle
feeding with breast milk.
• Comparison. Studies that include any infant formula,
including soy milk and cow’s milk-based formulas.
• Outcome. Studies that include any contagious infection
caused by bacteria, virus, or fungi.
Inclusion Criteria
Critical Appraisal
“Breast-feeding and Childhood Hospitalizations” by Tarrant et
al. (2010)
• Addresses clearly focused issue
• Cohort recruited in acceptable way
• Parental recall bias present when measuring exposure
• Bias minimized when measuring outcome
• Missing some follow-up information from parents
• Answers from parents contradictory at times
• Identified all important confounding factors
• No follow-up of subjects mentioned
• Results are precise to a confidence interval of 0.47-0.91
• Results are believable
• Study done in Hong Kong so unknown if results applicable to
USA
• JBI Level of Evidence: Level 3.c—cohort study with control group
“Breastfeeding and Hospitalizations for Diarrheal and
Respiratory Infection in the United Kingdom Millennium
Cohort Study” by Quigley, Kelly, and Sacker (2007)
• Addresses clearly focused issue
• Cohort recruited in acceptable way by random sampling
• Parental recall bias present when measuring exposure and
outcome
• Important confounding factors not specified, but it is stated a
wide range of confounders were adjusted for
• Follow-up of subjects not detailed
• Results are precise to a confidence interval of 0.47-0.92 for lower
respiratory tract infections (LRTI) and 0.18-0.78 for diarrheal
hospitalizations
• Results are believable
• Study done in UK so results can be applied to USA
• JBI Level of Evidence: Level 3.c—cohort study with control group
“Breastfeeding Helps Prevent Two Major Infant Illnesses” by
Story and Parish (2008)
• Addresses clearly focused question
• 15 published articles retrieved from 5 reliable databases
• Majority of articles included are large-scale, ranging from
170-2602 people, with seemingly high reliability and validity
• Assessment of quality of included studies is not discussed
• Reasonable to combine results from each study because all
concluded breastmilk can reduce infection rate in infants
• No confidence intervals listed for each included study, so
unknown how precise results are
• Included studies took place in USA, UK, Bangladesh, India, and
Brazil, so unknown if results applicable to local population
• All important outcomes were considered
• Benefits worth the harms and costs
• JBI Level of Evidence: Level 3.b—systematic review of
comparable cohort and other lower study designs
“Breast-feeding and Childhood Hospitalizations” by Tarrant et al. (2010)
• Study design: prospective population-based birth cohort
• Participants: 8327 children born in 1997 from one of 49 publicly funded Maternal
and Child Health Centers in Hong Kong
• Sampling design: cluster sampling unrelated to exposure
• Intervention: exposure to exclusive breastfeeding
• Comparison group: partial breastfeeding or never breastfed
• Outcome measures: viewed public hospital admission records
• Results: Exclusive breastfeeding for at least 3 months was associated with lower
risk of hospital admissions for infection in first 6 months (hazard ratio=0.61)
• Author conclusions: Breastfeeding provides substantial protection from
hospitalization for infectious disease in infancy
“Breastfeeding and Hospitalizations for Diarrheal and Respiratory Infection in
the United Kingdom Millennium Cohort Study” by Quigley, Kelly, and Sacker
(2007)
• Study design: retrospective cohort study
• Participants: 15890 singleton, term infants born in England, Wales, Scotland, and
Northern Ireland in 2000-2002
• Sampling design: random 2-stage sample
• Intervention: exposure to exclusive breastfeeding
• Comparison group: partial breastfeeding or never breastfed
• Outcome measures: parental report of hospitalizations for diarrhea and LRTIs in
first 8 months of life
• Results: monthly prevalence of LRTI in those exclusively breastfed was 30%,
compared to 49% of those never breastfed; 34% lower risk of getting an LRTI from
exclusive breastfeeding (OR=0.66); 63% lower risk of diarrheal hospitalization
from exclusive breastfeeding (OR=0.37)
• Author conclusions: Breastfeeding, particularly when exclusive and prolonged,
protects against severe morbidity in the UK
“Breastfeeding Helps Prevent Two Major Infant Illnesses” by Story and Parish
(2008)
• Study design: systematic review
• Participants: 15 large-scale studies, majority cohort studies, discussing effects of
breastfeeding on the incidence of GI and respiratory illnesses from 1997-2007
• Sampling design: identifying study eligibility criteria and completing extensive
search review among 5 databases
• Intervention: exposure to exclusive breastfeeding
• Comparison group: partial breastfeeding or never breastfed
• Outcome measures: parental questionnaires and in-person interviews on the
occurrence of hospitalizations and illness for diarrhea, pneumonia, and LRTIs
• Results: 5 included studies statistically significant for breastmilk decreasing
infection rate (p<0.05); 40% reduction in risk for GI illness in first year of life for
those breastfed; hospital admissions 4.91 times higher among infants never
breastfed
• Author conclusions: Protective relationship exists between breastfeeding and the
incidence of diarrhea and pneumonia
Extraction of Findings
• Advise soon-to-be and new mothers to breastfeed
their infants
• Educate new mothers on the importance of breast
milk on reducing infections
• Be aware that majority of the summarized
evidence is from parental questionnaires
• Increase knowledge on this topic by reviewing
other observational studies and evidence
summaries that discuss the biological effects of
breast milk on reducing infection
Implications for APNs
Effect of Breastfeeding on Infant Infection
Karissa Braden, RN, BSN
Purdue University Calumet
Synthesis of Findings
• After reviewing the extracted findings from each
study, it can be concluded from the summarized
evidence that breastfeeding’s effect on reducing
infant infections is significant compared to formula
feeding
• Exclusive breastfeeding significantly reduces the
incidence of infection in infants compared to
infants that have never breastfed
• The level of confidence in the evidence, related to
the critical appraisal of each study, is high
What is the effectiveness of breastfeeding, compared to formula feeding, in reducing infant infection?
Implications for Research
• Further research with more objective
measurements of exposure and outcomes to
minimize parental bias
• Further research that controls all possible
confounding factors
• Systematic reviews of comparable large-scale
cohort studies can be conducted to expand our
confidence in the results