Balancing fertility and child survival in developing world

Children in smaller families are only slightly more likely to survive childhood in high mortality environments, according to a new study of mothers and children in sub-Saharan Africa seeking to understand why women, even in the highest fertility populations in world, rarely give birth to more than eight children. The study by David Lawson and Alex Alvergne from UCL Anthropology, and Mhairi Gibson from the University of Bristol, challenges the popular theory proposed by evolutionary anthropologists that natural selection sets the upper limit of high fertility to balance a 'life history trade-off'' between fertility and child survival, with too many births believed to dangerously compromise a mother's ability to provide sufficient care for each child. The study also considers why fertility rates drop when societies become richer, a trend referred to as the demographic transition. The research, published today in the journal Proceedings of the Royal Society B: Biological Sciences , compiled information on over 150,000 mothers and their children from 27 sub-Saharan African countries using the Demographic and Health Surveys - national household surveys that record information on births, deaths and measures of health and socioeconomic status throughout the developing world. This enabled Lawson and colleagues to statistically test, with much more data than ever before, when and where high fertility places children at risk. Overall, the results confirm that mothers with many children are more likely experience the death of a child.