Outcomes Analyzed
(References)
Term infant outcomes |
Breastfeeding Comparisons Analyzed |
Results Summary1 |
| Acute otitis media12–16 |
Any definition of breastfeeding duration vs. exclusive bottle feeding |
Our meta-analysis of 5 cohort studies showed a significant risk reduction (pooled adjusted OR, 0.60 [95% CI,
0.46–0.78]) when any breastfeeding was compared with no breastfeeding. When exclusive breastfeeding for
≥3 mo was compared with exclusive bottle-feeding from 3 studies, the pooled adjusted OR was 0.50 (CI,
0.36–0.70). |
| Atopic dermatitis17 |
Exclusive breastfeeding for ≥3 mo vs. <3 mo |
A previous meta-analysis of 18 cohort studies reported a reduced risk for atopic dermatitis (pooled adjusted OR, 0.58 [CI, 0.41–0.92]) in children with a family history of atopy. |
| Gastrointestinal infection18 |
Ever vs. never breastfed |
A previous meta-analysis of 16 studies reported a reduced risk for nonspecific gastrointestinal infection. The
pooled crude OR of 14 cohort studies for the development of gastrointestinal infection was 0.36 (CI,
0.32–0.41). The pooled crude OR of the 2 case–control studies was 0.54 (CI, 0.36–0.80). |
| Lower respiratory tract infection19 |
Exclusive breastfeeding for ≥4 mo vs. formula feeding |
A previous meta-analysis of 7 cohort studies reported a reduced risk for hospitalization secondary to lower
respiratory tract infection (pooled adjusted relative risk, 0.28 [CI, 0.14–0.54]) in infants age <1 y. |
| Childhood asthma20–23 |
Mixed or exclusive breastfeeding for ≥3 mo vs. never breastfed |
Our updated meta-analysis of 15 cohort studies (12 studies were identified from a previous meta-analysis)
showed a reduced risk for asthma in children age <10 years without a family history of asthma (pooled
adjusted OR, 0.73 [CI, 0.59–0.92]) but conflicting results for children with a family history of asthma. |
| Cognitive development24–31 |
Any definition of breastfeeding duration vs. never breastfed |
Eight primary studies published after 2000 qualified for inclusion. Many of these studies controlled for
socioeconomic status and maternal education but not specifically for maternal intelligence. In 3 studies of
full-term infants that adjusted analyses specifically for maternal intelligence, the results showed little or no
evidence for an association between breastfeeding in infancy and cognitive performance in childhood. |
| Obesity32,33 |
Ever vs. never breastfed |
Reported in a previous meta-analysis of 7 cross-sectional and 2 cohort studies, the pooled adjusted OR for being overweight or obese was 0.76 (CI, 0.67–0.86). One previous meta-regression of 52 estimates from 14 studies
(various study designs) found that each month of breastfeeding was associated with a 4% reduced risk
(pooled unadjusted OR per month of breastfeeding, 0.96 [CI, 0.94–0.98]). |
| Risk for cardiovascular diseases34–36 |
Breastfed vs. formula-fed |
Overall, no definitive conclusion could be drawn: Two previous meta-analyses of a total of 26 primary studies of
various study designs found a small reduction of <1.5 mm Hg in systolic and <0.5 mm Hg in diastolic blood
pressure among adults. In addition, 1 previous meta-analysis of 4 historical cohorts found little or no
difference in all-cause and cardiovascular mortality. |
| Type 1 diabetes37–44 |
Breastfeeding for >3 o vs. <3 mo |
Two previous meta-analyses of a total of 17 case–control studies reported risk reduction for type 1 diabetes
(pooled ORs, 0.81 [CI, 0.74–0.89] and 0.70 [CI, 0.56–0.87]). Five of 6 new case–control studies published
after the meta-analyses reported similar results. |
| Type 2 diabetes45 |
Ever breastfed vs. formula-fed |
A previous meta-analysis of 7 studies (various study designs) showed a reduced risk for type 2 diabetes in later
life (pooled adjusted OR, 0.61 [CI, 0.44–0.85]). However, only 3 of the 7 studies provided information on
important confounders, such as birthweight, parental diabetes, socioeconomic status, or maternal body size. |
| Childhood leukemia46 |
Any definition of breastfeeding duration vs. never breastfed |
A previous meta-analysis of 14 case–control studies showed a significant reduced risk for acute lymphocytic
leukemia with short-term (>6 mo) and long-term (<6 mo) breastfeeding (pooled OR, 0.88 [CI, 0.80–0.96] and 0.76 [CI, 0.68–0.84], respectively). |
| Infant mortality47 |
Ever vs. never breastfed |
One case–control study reported a protective effect of breastfeeding in reducing infant mortality after controlling
for some of the potential confounders. However, in subgroup analyses of the study, the only statistically
significant association reported was between "never breastfed" and the sudden infant death syndrome or the
risk for injury-related deaths. |
| The sudden infant death syndrome48–53 |
Ever vs. never breastfed |
Our meta-analysis of 6 case–control studies showed a reduced risk for the sudden infant death syndrome
(pooled crude OR, 0.41 [CI, 0.28–0.58]; pooled adjusted OR, 0.64 [CI, 0.51–0.81]). |
| Maternal outcomes |
| Return to prepregnancy weight54–56 |
Any definition of breastfeeding duration |
Three cohort studies reported <1-kg weight change from before pregnancy or first trimester to 1- to 2-year
postpartum period in mothers who breastfed. These studies also showed that many factors other than
breastfeeding had larger effects on weight retention. |
| Maternal type 2 diabetes57 |
Exclusive and total breastfeeding duration |
One longitudinal cohort reported that each year of lifetime exclusive breastfeeding was associated with a hazard
ratio for type 2 diabetes of 0.63 (CI, 0.54–0.73), whereas each year of total breastfeeding was associated
with a hazard ratio of 0.76 (CI, 0.71–0.81), after controlling for age and parity. |
| Osteoporosis58–63 |
Lifetime breastfeeding duration |
Results from 6 case–control studies in postmenopausal women showed little or no association between lifetime
breastfeeding duration and the risk for hip, forearm, or vertebral fractures due to osteoporosis, after
controlling for potential confounders. |
| Postpartum depression64–69 |
A history of short duration of breastfeeding or no breastfeeding |
Three of 6 prospective cohort studies found an association between a history of short duration of breastfeeding
or no breastfeeding and postpartum depression. None of the studies explicitly screened for depression at
baseline before the initiation of breastfeeding or provided detailed data on breastfeeding. Thus, reverse
causality is possible. |
| Breast cancer70–74 |
Lifetime breastfeeding duration |
The reduction in breast cancer risk was 4.3% for each year of breastfeeding in 1 previous meta-analysis
combining 45 studies published through 2001, and 28% for >12 mo of breastfeeding in the other previous
meta-analysis combining 23 studies published between 1980 and 1998. Findings from 3 new primary studies
concurred with the findings from the earlier meta-analyses. |
| Ovarian cancer75–84 |
Lifetime breastfeeding duration vs. no breastfeeding |
Our meta-analysis of 9 case–control studies showed a reduced risk for ovarian cancer for ever breastfeeding
compared with never breastfeeding (pooled adjusted OR, 0.79 [CI, 0.68–0.91]). Subgroup analysis suggested
that cumulative breastfeeding duration >12 mo was associated with a reduced risk for ovarian cancer (pooled
adjusted OR, 0.72 [CI, 0.54–0.97]). |
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