Taking daily fish oil supplements during pregnancy can slash chances of a premature birth by up to 42 per cent, a major review has found.
Mothers-to-be have long been warned to limit oily fish and avoid certain fish altogether because of concerns over pollutants and mercury exposure.
Now researchers have found those who consume the highest levels of omega-3 fatty acids are significantly less likely to give birth early.
The findings are so strong they suggest pregnant women should start taking cod liver oil tablets every day from 12 weeks onwards.
A review of 70 studies found increasing a type of fatty acids found in oily fish like salmon and mackerel lowers the risk of having a baby born before 37 weeks by 11 per cent.
The risk of giving birth before 34 weeks drops by 42 per cent and the chances of having a small baby – weighing less than 5lbs 5oz – falls by a tenth (10 per cent).
Around 60,000 babies are born prematurely in the UK each year, while the figure is around 380,000 in the US.
Recent rankings put the UK 134th out of 184 countries in the world, higher than many countries in Europe and higher than Cuba, Ecuador and Iraq.
There are currently few options for preventing premature birth, yet it is the leading cause of death in children under-5 worldwide.
Those who survive facing a range of long-term conditions including visual impairment, developmental delay and learning difficulties.
But scientists suggest taking a daily pill – containing between 500 and 1000mg of long-chain omega-3 fats – from 12 weeks onwards could help to cut the risk.