The findings are based on almost 9000 children, who were part of the 1970 British Cohort Study, which regularly monitors a sample of the British population from birth onwards.
Relevant information was obtained at the children's birth, and at the ages of 5 and 10 years, from midwives and health visitors, parents, and teachers. This included how much the child weighed at birth and whether s/he was breastfed.
It also included factors that might influence or be linked with a child's reactions to stress and coping mechanisms, including maternal depression, parental education levels, their social class, and smoking habits.
When the children were 10 years old, their teachers were also asked to rate the anxiety of their pupils on a scale of zero to 50, while parents were interviewed about major family disruption, including divorce or separation, which had occurred when their child was between 5 and 10 years of age.
Unsurprisingly, when all the data were analysed, the findings pointed to a greater likelihood of high anxiety among children whose parents had divorced or separated.
But children who had been breastfed were significantly less anxious than their peers who had not been breastfed.
Breastfed children were almost twice as likely to be highly anxious, while children who had been bottle fed were over 9 times as likely to be highly anxious about parental divorce/separation.
The findings held true, irrespective of other factors likely to influence the results.
The authors emphasise that their research does not prove that breastfeeding itself makes children cope better with life stress; rather, it may be a marker of some other maternal or parental factors, they say.
But they cite animal research, which suggests that the quality of physical contact between mother and baby during the first few days of life may influence the development of the offspring's neural and hormonal pathways that are involved in the stress response. Babies with more of the type of contact experienced during breast feeding coped better with stress when older.
Breastfeeding may also affect the quality of the bonding between mother and child, and the way in which the two relate to each other. And this may have a lasting impact on the child's anxiety levels in response to stressful life events, the authors suggest.
[Breast feeding and resilience against psychosocial stress Online First Arch Dis Child 2006 doi: 101136/adc.2006.096826]