According to a study by Australian researchers premature babies who were given high doses of omega-3 fatty acid were less likely to have developmental delays - but this only applied to baby girls.
Premature babies are often born before their brains have fully developed and some are thought to have inadequate DHA while their brains are still growing and there is the suspicion that this amount may be insufficient for building brain matter in preemies.
Docosahexaenoic acid (DHA) is a long-chain omega-3 fatty acid which is needed for brain development - the best sources are fish such as tuna, herring and salmon - and foetuses rely on the mother to provide DHA via the placenta.
The researchers at the Women's and Children's Hospital and Flinders Medical Centre, in Adelaide, were interested in exploring the theory that an insufficient supply of the nutrient during the newborn period possibly increases the risk of developmental disorders and learning disabilities in babies born before 33 weeks' gestation.
Dr Maria Makrides and her colleagues tested the hypothesis in a trial with 657 premature babies from five Australian hospitals in order to determine the effect of high-dose dietary DHA on neurological outcomes in preterm infants.
The infants were given either a typical amount of DHA, as found in breast milk or formula, or a dose triple that amount, from day 2 to 4 of life until the infants reached their expected date of delivery.
Breast feeding mothers allocated to the high-DHA group were asked to consume six 500-mg DHA-rich tuna oil capsules per day to achieve a high breast milk DHA concentration and half the bottle-fed babies received regular formula and half received formula fortified with added DHA.
The scientists tested the formula and breast milk to ascertain DHA levels and each mother was instructed to maintain her assigned regimen until her preterm baby reached its expected birth date.
When the researchers measured the babies neurological development at 18 months they found that girls receiving extra DHA either in formula or breast milk scored higher on the tests and were 57% less likely to have a mild delay in mental development and 83% less likely to have a severe delay, compared with girls not getting the supplement.
However boys did not show any cognitive benefit from the DHA supplements and the researchers say this is puzzling and the reasons are unclear, but Dr Makrides says boys have a higher metabolic rate and she suggests they may burn more DHA as energy and may have a higher requirement for DHA.
The Australian study is the largest trial to test the supplement randomly in preterm babies and the researchers say the results support the hypothesis that preterm infants benefit from high level doses of DHA.
Dr Makrides says the level of DHA used in the study should become the new 'gold standard' for preterm infants, whether it is supplied through breast milk or infant formula.
The Australian team plans to monitor the children for seven years.