Breastfeeding and child behaviour at five years
Paper: Breastfeeding and child behaviour in the Millennium Cohort Study
Midwives magazine: Issue 4 :: 2011
Paper | Breastfeeding and child behaviour in the Millennium Cohort Study
Authors | Heikkilä K, Sacker A, Kelly Y, Renfrew MJ, Quigley MA.
Publication | Arch Dis Child 2011; doi: 10.1136/adc.2010.201970
Using data from a large, nationally representative UK cohort, the Millennium Cohort Study, the authors examined whether breastfeeding is associated with behavioural development in children aged five. Duration of breastfeeding, exclusively or at all, was ascertained from parental interview when the infants were nine months old. Child behaviour was assessed using a parent-completed strength and difficulties questionnaire (SDQ).
The analyses comprised white mother and singleton child pairs (non-white and mixed ethnic groups were excluded because a considerable proportion of these mothers did not respond to the questionnaire). Very premature infants (before 28 weeks) were also excluded. A total of 10,037 mother-child pairs were included in the analyses (9525 term and 512 preterm children). Breastfeeding initiation was equally common in term and preterm children (65% in both groups); 29% of term infants and 21% of preterm infants were breastfed for at least four months (mean duration was 9.8 and 9.6 months respectively).
In term children, breastfeeding was associated with lower odds of an abnormal total SDQ score. Term children who were breastfed for four months or longer had lower odds of an abnormal score, even after adjustment for potential confounders; exclusive breastfeeding for four months or longer was associated with lower odds of emotional and conduct scores. The associations of breastfeeding and hyperactivity, peer problems or pro-social scores varied from positive to negative.
In preterm children, being breastfed for three months or longer was associated with lower odds of an abnormal SDQ score, although adjustment for potential confounders considerably attenuated these estimates.
Overall, the findings were similar to those in many previous studies. The findings were also consistent for exclusive and any breastfeeding. The authors concede that the breastfed children may be growing up in families that are different from formula-fed children in terms of parenting or other unmeasured confounders.
Breastmilk contains large amounts of essential long-chain polyunsaturated fatty acids, growth factors and hormones, which the authors consider to have an important role in the development and function of the brain and central nervous system. In the past decade, many manufacturers have begun to supplement formulas with essential fatty acids, so the children in this study are likely to have received supplemented formulas, which would have diluted any associations. It could be that breastfeeding leads to more interaction between mother and child, better learning of acceptable behaviours and fewer behavioural problems. Also, formula-feeding is associated with infections and hospitalisations during infancy, which could lead to behavioural problems in children, perhaps due to time spent separated from the parents.
The researchers stress that the important strengths of the study are that they used a large prospectively collected dataset and adjusted their analyses for a large number of potential confounders.
Overview
In this study of white UK children, breastfeeding for four months or longer was associated with lower odds of behavioural problems at five years. In term children, this association remained, even after adjustment for potential confounders.
Jan wallis is a retired midwife and senior lecturer
