Children whose mothers get enough omega-3 fatty acid during pregnancy may have sharper problem-solving skills in infancy, a small study suggests.

Researchers found that 9-month-olds whose mothers had eaten DHA-fortified bars during pregnancy performed better on a test of problem-solving abilities than infants whose mothers had not added DHA to their diets.

DHA, or docosahexaenoic acid, is one of the major omega-3 fatty acids found in oily fish like salmon, sardines and tuna. Because of the fat's vital role in brain development, experts recommend that pregnant women get 300 milligrams (mg) of DHA each day.

However, research shows that few U.S. women meet this goal.

The new findings, published in the American Journal of Clinical Nutrition, suggest that women who do get adequate DHA may aid their infants' cognitive abilities.

The study included 29 women in their 24th week of pregnancy. Half were randomly assigned to eat a cereal bar supplemented with 300 mg of DHA from fish oil, while the rest were given a bar with added corn oil to serve as a comparison. On average, the women ate five bars per week.

Their babies underwent standard tests of infant problem-solving and memory at the age of 9 months. The problem-solving task tested the infants' ability to retrieve a toy that was covered by a cloth.

In general, the researchers found, babies in the DHA group performed better on the test than those in the comparison group. There was no difference between the two groups on the memory test.

It's not entirely clear what the better problem-solving performance at 9 months of age will mean later in life. However, other studies have found that DHA supplements during pregnancy seem to offer a "developmental advantage" later in childhood as well, Dr. Carol J. Lammi-Keefe, a co-author on the current study, told Reuters Health.

One study found that giving women fish oil during pregnancy and during the first few months of breastfeeding seemed to boost their children's IQ scores at age 4.

"DHA during pregnancy has benefits for infant neural development, and most pregnant women can benefit from increasing the intake of DHA in their diets," said Lammi-Keefe, of Louisiana State University in Baton Rouge.

Women can go a "long way" toward getting 300 mg of DHA per day by eating a couple tuna fish sandwiches, plus a serving of fatty fish like salmon, each week, according to Lammi-Keefe.

Other sources of DHA, she noted, include fish oil pills and algae-derived DHA, which is included in some prenatal vitamins.

Pregnant and breastfeeding women should avoid certain fatty fish, however, because they could have high mercury levels. These include shark, swordfish, king mackerel and tile fish.