i posted this a while ago, but you might like to read it thedm
I found this hereits a pdf file of a meta-analysis of loads of breastfeeding studies - all in developed countries. It makes for interesting reading. I'll just cut and paste a few bits so you get the gist (and no, i wont cherrypick! )
We screened over 9,000 abstracts. Forty-three primary studies on infant health outcomes, 43
primary studies on maternal health outcomes, and 29 systematic reviews or meta-analyses that
covered approximately 400 individual studies were included in this review.
The association studies of breastfeeding and health outcomes mostly presented results as odds
ratios. To facilitate interpretation of the odds ratio, we chose to present these data as a reduction in
relative risk, estimated as ?(1 ? odds ratio) x 100%,? along with the corresponding 95% confidence
interval (CI).
Full term Infant Outcomes
Acute Otitis Media.
Our meta-analysis of five cohort studies of good and moderate
methodological quality showed that breastfeeding was associated with a significant reduction in the
risk of acute otitis media. Comparing ever breastfeeding with exclusive formula feeding, the risk
reduction of acute otitis media was 23 percent (95% CI 9% to 36%). When comparing exclusive
breastfeeding with exclusive formula feeding, either for more than 3 or 6 months duration, the
reduction was 50 percent (95% CI 30% to 64%). These results were adjusted for potential
confounders.
Atopic Dermatitis.
One good quality meta-analysis of 18 prospective cohort studies on full term
infants reported a reduction in the risk of atopic dermatitis by 42 percent (95% CI 8% to 59%) in
children with a family history of atopy and exclusively breastfed for at least 3 months compared with
those who were breastfed for less than 3 months. The meta-analysis did not distinguish between
atopic dermatitis of infancy (under 2 years of age) and persistent or new atopic dermatitis at older
ages. It has been postulated that the diagnosis of atopic dermatitis in patients younger than 2 years of
age could be attributed to infectious etiologies, which may be prevented by breastfeeding. However,
a stratified analysis by duration of followup found the risk reduction from breastfeeding was similar
in subjects with less than 2 years compared with more than 2 years of followup.
Gastrointestinal Infections.
For non-specific gastroenteritis, one systematic review identified
three primary studies that controlled for potential confounders. These studies reported that there was
a reduction in the risk of non-specific gastrointestinal infections during the first year of life in
breastfed infants from developed countries. But a summary adjusted estimate taking into account
potential confounders could not be determined because the studies did not provide usable quantitative
data. However, a recent case-control study from England that took into account the role of potential
confounders reported that infants who were breastfeeding had a 64 percent (95% CI 26% to 82%)
reduction in the risk of non-specific gastroenteritis compared with infants who were not
breastfeeding.
Lower Respiratory Tract Diseases.
The summary estimate from a good quality meta-analysis
of seven studies reported an overall 72 percent (95% CI 46% to 86%) reduction in the risk of
hospitalization due to lower respiratory tract diseases in infants less than 1 year of age who were
exclusively breastfed for 4 months or more. The results remained consistent after adjustment for
potential confounders.
Asthma.
The studies on asthma were equivocal. A previously published good quality metaanalysis
reported a moderate protective effect and four recent primary studies reaching mixed
conclusions, including two studies finding an increased risk of asthma associated with breastfeeding.
We updated the meta-analysis with the new studies. Our analysis showed that breastfeeding for at
least 3 months was associated with a 27 percent (95% CI 8% to 41%) reduction in the risk of asthma
in those subjects without a family history of asthma compared with those who were not breastfed.
For those with a family history of asthma, there was a 40 percent (95% CI 18% to 57%) reduction in
the risk of asthma in children less than 10 years of age who were breastfed for at least 3 months
compared with those who were not breastfed. However, the relationship between breastfeeding and
the risk of asthma in older children and adolescents remains unclear and will need further
investigation.
Cognitive Development. One well-performed sibling analysis and three prospective cohort
studies of full-term infants, all conducted in developed countries, adjusted their analyses specifically
for maternal intelligence. The studies found little or no evidence for an association between
breastfeeding in infancy and cognitive performance in childhood. Most of the published studies
adjusted their analyses for socioeconomic status and maternal education but not specifically for
maternal intelligence. For those studies that reported a significant effect after specific adjustment for
maternal intelligence, residual confounding from other factors such as different home environments
cannot be ruled out.
Obesity.
Three meta-analyses of good and moderate methodological quality reported an
association of breastfeeding and a reduction in the risk of obesity in adolescence and adult life
compared with those who were not breastfed. One study reported the reduction in the risk of
overweight/obesity in breastfeeders compared with non-breastfeeders was 24 percent (95% CI 14%
to 33%); another study reported 7 percent (95% CI 1% to 12%). Both of these estimates took into
account the role of potential confounders. Furthermore, they also showed that the magnitude of
association decreased when more confounders were entered into the analyses. The third study used
meta-regression and found a 4 percent reduction in the risk of being overweight in adult life for each
additional month of breastfeeding in infancy. Overall, there is an association between a history of
breastfeeding and a reduction in the risk of being overweight or obese in adolescence and adult life.
One should be cautious in interpreting all these associations because of the possibility of residual
confounding.
Risk of Cardiovascular Diseases.
Results from two moderate quality meta-analyses concluded
that there was a small reduction of less than 1.5 mm Hg in systolic blood pressures and no more than
0.5 mm Hg in diastolic blood pressures among adults who were breastfed in their infancy compared
with those who were formula-fed. The association weakened after stratification by study size,
suggesting the possibility of bias in the smaller studies.
One meta-analysis of cohort and case-control studies reported that there was a reduction in total
and LDL cholesterol levels by 7.0 mg/dL and 7.7 mg/dL, respectively, in adults who were breastfed
during infancy compared with those who were not. However, these findings were based on data from
adults with a wide age range. The analysis did not segregate the data according to gender and
potential confounders were not explicitly analyzed. Detailed information (e.g., fasting or non-fasting)
on the collection of specimen for cholesterol testing was not included. Because of these deficiencies,
the correct characterization of a relationship between breastfeeding and adult cholesterol levels
cannot be determined at this time.
One meta-analysis found little or no difference in all-cause and cardiovascular mortality between
adults who were breastfed during infancy and those who were not. There were possible biases and
limitations in the studies reviewed, however. Presence of statistical heterogeneity across studies
suggests that it may not have been appropriate to combine estimates from individual studies into one
summary estimate. Because of these reasons, no definitive conclusion could be drawn regarding the
relationship between a history of breastfeeding and cardiovascular mortality.
In summary, the relationship between breastfeeding in infancy and the risk of cardiovascular
diseases cannot be confidently characterized at this time and will need further investigation.
Type 1 Diabetes.
Two moderate quality meta-analyses suggest that breastfeeding for at least 3
months reduced the risk of childhood type 1 diabetes compared with breastfeeding for less than 3
months. One reported a 19 percent (95% CI 11% to 26%) reduction; the other reported a 27 percent
(95% CI 18% to 35%) reduction. In addition, findings from five of six studies published since the
meta-analyses reported similar results. However, these results must be interpreted with caution
because of the possibility of recall biases and suboptimal adjustments for potential confounders in the
studies.
Type 2 Diabetes.
In one well-performed meta-analysis of seven studies of various designs,
breastfeeding in infancy was associated with a 39 percent (95% CI 15% to 56%) reduced risk of type
2 diabetes in later life compared with those who were not. However, only three of seven studies
adjusted for all the important confounders such as birth weight, parental diabetes, socioeconomic
status, and individual or maternal body size. Though the crude and adjusted estimates did not differ
in these three studies, the lack of adjustments for potential confounders such as birth weight and
maternal factors by all studies could exaggerate the magnitude of an association.
Childhood Leukemia.
The published studies on childhood acute lymphocytic leukemia (ALL)
were equivocal; a good quality meta-analysis reported a moderate protective effect from
breastfeeding and the other good quality systematic review reached the opposite conclusion. We
conducted a meta-analysis including only good and fair quality case-control studies identified in the
systematic review, since the meta-analysis did not provide methodological quality grading of primary
studies. We found breastfeeding of at least 6 months duration was associated with a 19 percent (95%
CI 9% to 29%) reduction in the risk of childhood ALL. The previous meta-analysis also reported an
association between breastfeeding of at least 6 months duration and a 15 percent reduction (95% CI
2% to 27%) in the risk of acute myelogenous leukemia (AML). Overall there is an association
between a history of breastfeeding for at least 6 months duration and a reduction in the risk of both
leukemias (ALL and AML).
Infant Mortality.
One study of moderate methodological quality evaluated the relationship
between breastfeeding and infant mortality. The 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 Sudden Infant Death Syndrome (SIDS) or the risk of injury-related deaths.
Because of the limited data in this area, the relationship between breastfeeding and infant mortality in
developed countries remains unclear. Further investigation is needed.
Sudden Infant Death Syndrome (SIDS).
We conducted a meta-analysis by including only
studies that reported clear definitions of exposure, outcomes, and results adjusted for well-known
confounders or risk factors for SIDS. Our meta-analysis of seven case-control studies found that a
history of breastfeeding was associated with a 36 percent (95% CI 19% to 49%) reduction in the risk
of SIDS compared to those without a history of breastfeeding.
me again There is also a section on preterm infants and the effects of BF on the mother. I didnt want to push my luck with trying to send such a HUMONGOUS post!
oh, and otitis media is ear infection
I am a little surprised actually at some of the supposed benefits (reduced risk of osteoporosis for example) that were not found to be statistically significant, but relieved to find that a lot of the wonders of breastfeeding that i have taken to be fact, without checking properly are actually true.
I always knew breastfeeding was brill etc, but its good to have the figures to back it up - even if some of them aren't as unequivocal as one would hope