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Prolonged breastfeeding and malnutrition: confounding and effect modification in a Brazilian cohort study
C G Victora1, S R Huttly, F C Barros
1Departamento de Medicina Social, Universidade Federal de Pelotas, Brazil.
Insights
Prolonged breastfeeding showed no clear nutritional benefit and may be linked to poorer growth in children over 20 months. Socioeconomic status impacts this association, highlighting the need for nuanced recommendations on extended breastfeeding.
Area of Science:
- Pediatrics
- Nutritional Science
- Public Health
Background:
- Breastfeeding duration is debated regarding its impact on child growth.
- Previous studies show mixed results on the association between breastfeeding and anthropometric status.
- Socioeconomic factors may influence the relationship between breastfeeding and child development.
Purpose of the Study:
- To investigate the association between prolonged breastfeeding and anthropometric status in Brazilian children.
- To explore how socioeconomic status modifies the effect of breastfeeding on child growth.
- To inform public health policies regarding breastfeeding recommendations.
Main Methods:
- Population-based cohort study of 5,914 liveborns in Pelotas, Brazil.
- Assessment of anthropometric status at various ages (12, 20, and 43 months).
- Analysis controlling for confounding variables and effect modification by socioeconomic status.
Main Results:
- No significant association between breastfeeding at 12 months and anthropometric status.
- Breastfeeding at 20 and 43 months was associated with poorer anthropometric status in the general population.
- In low-income families, breastfeeding was linked to better growth, but this effect diminished after controlling for confounders. In higher-income families, non-breastfed children showed better growth.
Conclusions:
- Confounding and effect modification by socioeconomic status likely contribute to the controversy surrounding prolonged breastfeeding's nutritional effects.
- The nutritional impact of breastfeeding beyond the first year is complex and population-specific.
- Decisions on promoting extended breastfeeding should consider population characteristics and breastfeeding's non-nutritional benefits (anti-infective, birth-spacing).
Abstract:
We examined the association between prolonged breastfeeding and anthropometric status in a population-based cohort study of 5,914 liveborns from the city of Pelotas in Southern Brazil. When children from all socioeconomic groups were studied, there was no important association between current breastfeeding and anthropometric status at age 12 months. Children who were still breastfed at age 20 months--and, to a lesser extent, at 43 months--presented with poorer anthropometric status than their nonbreastfed counterparts. We did not find the same pattern in all socioeconomic groups, however. Children from low-income families who were breastfed tended to present better anthropometric status than those who were not, whereas the reverse was observed for children of middle- and high-income families. After controlling for confounding variables, the nutritional advantage of breastfeeding among low-income families was no longer clear, while the superiority of nonbreastfed infants amongst middle- and high-income children persisted. These findings indicate that some of the controversy regarding the nutritional effects of prolonged breastfeeding may have been caused by confounding and effect modification. Any decisions on whether or not breastfeeding should be encouraged after the first year of life should take into account the characteristics of the population as well as the anti-infective and birth-spacing properties of breastfeeding.