Association between breastfeeding and overweight in young children
Hediger, M. L. et al. JAMA 285:2453-2460, 2001
Risk of overweight among
adolescents who were breastfed as infants
Two US-based studies, one by the Harvard Medical School and the other by the National Institute of Child Health and Human Development, reported their findings relating infant feeding history to overweight status.
Hediger's study measured the height and weight of 2685 US children between the ages of three and five years. Infant feeding history was collected, including duration of breastfeeding and the age of introduction of solids. The study determined that breastfeeding protected against the development of overweight, but did not determine a statistical significance between breastfeeding and the reduced risk of becoming overweight.
The sample size of the study by Gillman et al was considerably larger. His team analysed approximately 15,000 young adolescents between the ages of nine to 14 years. Their mothers reported the duration of breastfeeding, the exclusivity of breastfeeding and when solids were first introduced. During the first six months of life, 62 per cent of the subjects had been only or mostly breastfed and 31 per cent were mostly fed infant formulas. At ages nine to 14, the children who were almost exclusively breastfed for the first six months were 22 per cent less likely to become overweight as adolescents. The authors also reported a dose dependent effect -- those who had been breastfed for at least seven months had a lower risk than those who reported breastfeeding for three months or less. The timing of introduction of solids was not related to risk of becoming overweight.
Although the Gillman study did not determine a direct link between breastfeeding and the reduced risk for obesity, they did postulate that the higher levels of insulin in formula fed babies could explain the higher accumulation of fat. Also, bottle fed infants have less ability to self regulate the amount of formula consumed.
These findings confirm a recent study from Germany demonstrating a reduced rate of obesity for five- to six-year-old children who had been breastfed.
Iron supplementation of breast-fed Honduran and Swedish infants from 4 to 9 months of age.
Domellöf, M. et al. J of Pediatr 138: 679-687, 2001
Iron supplementation for breastfed infants is a controversial practice in Canada where the prevalence of iron deficiency anaemia (IDA) amongst infants is low, and the consequence of prophylactic supplementation of healthy term breastfed infants is unknown. Healthy term infants are born with adequate iron stores to meet their needs for about the first six months of age. It is recommended that foods rich in iron be part of the complementary food diet commencing by six months of age while continuing breastfeeding.
The study be Domellöf et al sought to determine the effect of iron supplementation on haemoglobin and iron status in a population where IDA is prevalent (Honduras) and where IDA is low (Sweden). The study, designed as a randomized, placebo-controlled clinical trial, divided the infants into three groups:
The results showed that in the Honduran population iron supplementation from six to nine months significantly reduced the prevalence of IDA There was no advantage to beginning the supplements at four months compared with six months. In the Swedish population there was no significant reduction in risk of IDA.
The study results also suggested that the regulation of iron absorption and haemoglobin synthesis are independently regulated. This suggests to the authors that if iron-sated infants are not able to "downregulate the absorption of supplemental iron", then "extended iron supplementation would increase the risk for iron overload, which may have adverse long-term effects." The authors also observed that, in this cohort, iron supplementation impaired linear growth.
The authors conclude that supplementation in populations where IDA is uncommon is not beneficial and may be harmful before six months of age.
The impact of pacifier use on breastfeeding: a prospective cohort study
Vogel, A.M. et al. J of Pediatr. Child Health 37: 58-63, 2001-07-13
Another pacifier study, this time from New Zealand, shows the negative impact of frequent pacifier use and looks at the 'predictors' of pacifier use and how pacifiers influence the duration of breastfeeding.
A prospective cohort study methodology was used to follow 350 mother and infant pairs for one year.
Early cessation of breastfeeding
Finger sucking was not associated with increased risk of early cessation of breastfeeding.
Duration of full breastfeeding (no supplementation with formula or solid foods but juice and water was allowed)
Risk factors for pacifier use
The authors concluded that it seems "appropriate to discourage regular pacifier use in breastfeeding infants" and that occasional use does not appear to be detrimental to breastfeeding.
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