Having a large number of children is bad for parents' health - particularly that of mothers, a study suggests. US researchers looked at 21,000 couples living in Utah between 1860 and 1985, who bore a total of 174,000 children. It was found the more children couples had, the worse their health and the more likely they were to die early. The Proceedings of the National Academy of Science study is historical, but the experts say it helps explain both the menopause and modern family planning. In other species, the high physical costs of bearing and raising offspring explain why having...