Now we know that mothers who take DHA supplements while pregnant reduce the chances of their babies being born preterm and at a low birth weight

The first phase of a 10-year, double-blind randomized controlled trial to determine whether prenatal nutritional supplementation with the omega-3 fatty acid DHA benefits children’s intelligence and school readiness has yielded results that greatly strengthen the case for the dietary supplement.

Infants whose mothers took 600 milligrams of DHA in the last half of gestation weighed more at birth and fewer of them were born before 34 weeks gestation than mothers who were given a placebo.

“A reduction in early preterm and very low birth weight delivery has clear clinical and public health signi cance,” said Susan Carlson, who directed the study with John Colombo.

DHA (docosahexaenoic acid) occurs naturally in cell membranes with the highest levels in brain cells, but levels can be increased by diet or supplements. An infant obtains DHA from his or her mother in utero and postnatally from human milk, but the amount received depends upon the mother’s DHA levels.

“U.S. women typically consume less DHA than women in most of the developed world,” said Carlson.

The next phase of the study will continue to follow the children of the 350 mothers who were enrolled in the study during pregnancy. During the first five years of the study, all children received multiple developmental assessments through 18 months of age.

In the next five years, all children will receive twice-yearly assessments through six years of age. The researchers will measure developmental milestones that occur in later childhood and are linked to lifelong health and welfare.

Previous research has established the effects of postnatal feeding of DHA on infant cognitive and intellectual development, but DHA is accumulated most rapidly in the brain during pregnancy, said Colombo. “That’s why we are so interested in the effects of DHA taken prenatally, because we will really be able to see how this nutrient affects development over the long term.”

According to Carlson, the possibility that DHA may have long-term benefits for cognitive-intellectual development, particularly on measures that predict school achievement, would have enormous implications for public policy on prenatal nutrition.