Causes of major birth defects remain largely unknown, according to a new study.
The researchers, based at the University of Utah School of Medicine, were only able to establish a definite cause in one in every five of the 5,504 babies with birth defects they studied.
They warned, in the paper published in the British Medical Journal (BMJ) on Tuesday 30 May: “Unless progress is made in identifying and preventing the root causes of birth defects, these conditions will continue to have draining effects on the survival and health of individuals, families, and countries.”

Previous studies have shown that factors such as maternal diabetes, smoking and obesity are associated with an increased risk of birth defects, but translating…