A million babies die each year because they are born too early. There isn’t a lot that can be done to stop a premature delivery, but a new study suggests that mothers-to-be who want to reduce the odds of premature birth should take omega-3 supplements to reduce the risk of giving birth early.

Prematurity is the leading cause of death for children under the age of five worldwide. Those children who survive an early birth have a higher risk of many long-term health problems. Long-chain fatty acids may play a role in reducing the risk of premature births. Two fatty acids have been of particular interest: DHA and EPA. These fatty acids are found in fatty fish like albacore tuna, salmon and herring, and in fish oil supplements. DHA and EPA are known as omega-3 fatty acids because of their chemical structure.

Two fatty acids have been of particular interest: DHA and EPA.

Researchers reviewed 70 studies and found that when pregnant women increased their daily intake of omega-3 fatty acids, the risk of delivering a baby prematurely — before 37 weeks — went down by 11 percent; the risk of having a baby before 34 weeks went down 42 percent; and the chance of having a baby weighing less than 5 ½ pounds went down by 10 percent.

The Cochrane Pregnancy and Childbirth review concluded that there is sufficient evidence for omega-3 supplements to be used as a strategy for preventing early birth. “There are not many options for preventing premature birth, so these new findings are very important for pregnant women, babies and the health professionals who care for them,” said Philippa Middleton, PhD, from Cochrane Pregnancy and Childbirth and the South Australian Health and Medical Research Institute. “We don't yet fully understand the causes of premature labour, so predicting and preventing early birth has always been a challenge. This is one of the reasons omega-3 supplementation in pregnancy is of such great interest to researchers around the world.”

The Food and Drug Administration recommends that pregnant women eat two to three servings of fish each week, but certain fish — like tuna and swordfish — should be avoided or eaten only occasionally because of their high mercury levels. Pregnant women should discuss the use of omega-3 supplements with their physician.

The review was published in Cochrane Review.