Evidence to link cot death to hearing difficulties has been found by a British doctor working in America.

A study by Daniel Rubens at the Seattle children’s hospital in Washington state suggests babies who suffer injury to their ears during birth are at higher risk of cot death. It raises the prospect that hearing tests for infants could be used to warn of a heightened risk of cot death, also known as sudden infant death syndrome (Sids).

The causes of many cot deaths remain a mystery although numbers have halved since the early 1990s after a campaign advising parents to ensure babies do not sleep on their front. In Britain, the publicity drive was spearheaded by Anne Diamond, the BBC broadcaster whose five-month-old son Sebastian died from the syndrome in 1991. Cot death claims the lives of around 300 infants a year in Britain.

Last week, she was said to be “reading with interest” the Rubens evidence.

Experts are divided on whether there are one or many causes behind cot deaths, but other theories put forward include inhalation of parents’ cigarette smoke.

Rubens’s research, published in the journal Early Human Development, found that a surge of blood from the placenta during normal births, which is designed to kick-start breathing, may in some cases damage the workings of the inner ear.

In particular, the sudden increase in blood pressure can damage cells in the inner ear, which detect higher sound frequencies, a loss of which can be identified by tests during early infancy.

Rubens, a paediatric anaesthetist, says some of the cells may also have a second purpose as part of an early warning system to the brain that oxygen levels are falling in the baby’s blood.

If cells are damaged, this early warning relay is turned off and so babies with weaker lungs are at greater risk from choking or suffocation from overheating or a cramped position in a cot.

“Every parent knows the terrible fear of cot death, because it’s so mysterious and strange. Now we can guard against it, but it still carries off too many infants around the world,” said Rubens.

His work is based on a snapshot of 31 babies who have died over the past 13 years from the Sids in America’s smallest state, Rhode Island. He found that every victim had tests revealing a hearing problem. “That research was only the beginning. I shall be working with two different British groups taking this research further, and I hope to expand it to track 100,000 British babies.”

Rubens’s research correlates with other studies linking cot deaths with mothers who had long labour, when ear injuries may have been more prevalent. “We need to ask whether having a C-section birth might reduce cot deaths,” he said. “It’s a tragedy we should be able to understand.”

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