Findings show lack of benefit of prenatal DHA supplementation on IQ in children

Longer-term follow-up of a randomized trial found strong evidence for the lack of benefit of prenatal DHA supplementation on IQ in children at 7 years of age, according to a study published by JAMA.

The sale of prenatal supplements with docosahexaenoic acid (DHA) continues to increase, despite little evidence of benefit to offspring neurodevelopment. Maria Makrides, B.Sc., B.N.D., Ph.D., of the South Australian Health and Medical Research Institute, Adelaide, Australia and colleagues randomized pregnant women to receive 800 mg of DHA daily or a placebo during the last half of pregnancy and found no group differences in cognitive, language, and motor development at 18 months of age.

At 4 years of age there was no benefit of DHA supplementation in general intelligence, language, and executive functioning, and a possible negative effect on parent-rated behavior and executive functioning. This follow-up was designed to evaluate the effect of prenatal DHA on intelligence quotient (IQ) at 7 years, the earliest age at which adult performance can be indicated.

Of those eligible, 543 children (85 percent) participated in the 7-year follow-up. Average IQ of the DHA and control groups did not differ (98.31 for the DHA group vs 97.32 for the control group). Direct assessments consistently demonstrated no significant differences in language, academic abilities, or executive functioning. Although perceptual reasoning was slightly higher in the DHA group, parent-reported behavioral problems and executive dysfunction were worse with prenatal DHA supplementation.

The authors note that the small but consistent negative effects of prenatal DHA on behavior and executive functioning at 7 and 4 years may reflect true effects, although effect sizes were small and neurodevelopmental diagnoses did not differ between groups.