Maternal characteristics influence response to DHA during pregnancy

• We provide the first exploration of differential responses to maternal DHA supplementation in pregnancy in the context of a clinical trial.
• Our results highlights the fact that there are subgroups who respond differently to prenatal DHA supplementation during pregnancy.
• DHA intervention appeared to result in heavier babies and fewer low birth weight babies, but only in non-smoking women.
• Maternal DHA supplementation had mixed results for developmental outcomes of children depending on maternal education.
• We recommend that comparable RCT's pool data in a more diverse sample with greater power to identify possible responders to DHA supplementation.

We explored the degree to which maternal and offspring outcomes resulting from consuming prenatal docosahexaenoic acid (DHA, 800 mg/day) in a clinical trial were influenced by maternal characteristics. Among non-smokers, women who received DHA had heavier babies (adjusted mean difference (MD)=99 g 95% CI 45–153, p<0.01; interaction p=0.01) and fewer low birth weight babies than control women (adjusted relative risk=0.43 95% CI 0.25–0.74, p<0.01; interaction p=0.01). From women who had not completed further education, children in the DHA group had higher cognitive scores at 18 months compared with control children (adjusted MD=3.15 95% CI 0.93–5.37, p=0.01; interaction p<0.01). Conversely, the children of women who completed further education in the DHA group had lower language scores than control children (adjusted MD −2.82 95% CI −4.90 to −0.73, p=0.01; interaction p=0.04). Our results support the notion that responsiveness to prenatal DHA may depend on the characteristics of specific population subgroups.