Nearly half of all births in China are delivered by caesarean section, the world's highest rate, according to a survey by the World Health Organization - a shift toward modernization that isn't necessarily a good thing.The boom in unnecessary surgeries is jeopardizing women's health, the U.N. health agency warned in the report published online Tuesday in the medical journal The Lancet. Unnecessary C-sections are costlier than natural births and raise the risk of complications for the mother, said the report surveying nine Asian nations. It noted C-sections have reached "epidemic proportions" in many countries worldwide. The most dramatic findings were in China, where 46 per cent of births reviewed were C-sections - a quarter of them not medically necessary, the report said.