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Duration and
Exclusivity Of Breastfeeding
Cureent US recommenations for infant feeding include exclusive
breastfeeding for approximately the first 6 months and partial
breastfeeding with complementary foods for 12 months or longer as
desired; however, the most recent infant-feeding surveys indicate
that only approximately 60% of US women initiate breastfeeding, and
only approximately 29% continue to 6 months of age. Although most
mothers are likely to recognize that breastfeeding is beneficial for
their infants, questions may arise regarding optimal breastfeeding
duration and how the introduction of other foods and fluids may
affect the immunologic benefits.
Although a great deal of research has been conducted in the past 2
decades regarding the health consequences of breastfeeding, only
recently have studies been designed adequately to examine the
effects of specific infant feeding practices. In addition to the
prospective studies summarized in this article, several large
cross-sectional surveys of maternal and infant health have included
detailed questions regarding infant feeding patterns.
Using data from the US National Maternal and Infant Health Survey,
Raisler et al examined the effect of breastfeeding dose on infant
illness in the first 6 months of life. After exclusion of very low
birth weight infants and those without adequate data on infant
feeding , 7092 infants remained in the analyses. Breastfeeding rates
were generally lower in this sample because of the inclusion of low
birth weight infants and disadvantaged populations; only 40% of
mothers in the sample initiated breastfeeding and only 16% were
breastfeeding at 6 months.
Only 30% of mothers fully breastfed
their infants at 1 month, and less than 2% were fully breastfeeding
at 6 months. Using the ratio of breastfeedings to other feedings of
other foods and fluids in the infant's diets, breastfeedings dose
was categorized as (1) full (all breastfeedings), (2) most
(breastfeeds > other feeds), (3) equal (breastfeeds = other feeds),
and (4) less (breastfeeds < other feeds).
Compared with infants who were not
breastfed, all lavels of breastfeeding had lower odds ratios of
diarrhea, cough or wheeze, and vomiting .
Full breastfeeding among children
without siblings reduced the risk for OM, colds, and fever compared
with other feeding groups. A doseresponse effect of breastfeeding
was found for protection against diarrhea and for colds among
children without siblings, suggesting that a threshold level of
breastfeeding is necessary to confer protection. This result
remained significant among all income groups. The presence of
siblings altered the relationship between breastfeeding and colds,
OM, and fever, suggesting that the stress of exposure to related
pathogens carried by older siblings may be too great on infant's
immune systems.
Using data from a survey of 8501 monthers in Bristol, Baker et al
found that breastfeeding for 3 or more months reduced the prevalence
of wheeze and diarrhea in the first 6 months of life. Resulth
remained significant after controlling for several confounders,
including maternal smoking, crowded housing conditions, and the
presence of siblings.
Several of the longitudinal studies reported here indicate that
protection against infections illness is greatest with greater
intensity of breastfeeding even among affluent populations. Also
,breastfeeding durations of at least 3 months are commonly
associated with a reduced risk for infants' illness ; however, few
infants in these populations were breastfed intensively longer than
the first 3 months, limiting the ability of the researchers to
determine an optimal duration of exclusive breastfeeding.
Evidence is also building that breastfeeding protects infants
against illness beyond weaning, as indicated by several studies that
included follow-up of infants beyond the first few months of
life.Given the effects of breastfeeding in priming the infant immune
system, these associations are biologically plausible.
Together, these data indicate that breastfeeding is effective in
reducing the risk for illness among infants even in relatively
affluent populations and that exclusive breastfeeding for at least 3
months confers greater protection than dose less intense
breastfeeding for shorter durations. As numbers of infants
exclusively breastfed for 6 months increase, questions regarding how
longer durations of exclusive breastfeeding affect infact health may
be addressed. In the interim, most studies meeting the criteria of
Bauchner et al support the importance of breastfeeding as a means
of protection against acute infectiouns illness for infants and
young children.
(The Pediatric Clinic of North America)
BREASTFEEDING 2001, PART I:
THE EVIDENCE FOR BREASTFEEDING
Volume 48.Number1.February 2001
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