NORTH ADELAIDE, Australia—Uncertainty about the benefits of dietary docosahexaenoic acid (DHA) for pregnant women and their children exists, despite international recommendations that pregnant women increase their DHA intakes. As a result, researchers sought to determine whether increasing DHA during the last half of pregnancy would result in fewer women with high levels of depressive symptoms and enhance the neurodevelopmental outcome of their children (JAMA. 2010;304(15):1675-1683). In a double bind, multicenter, randomized controlled trial, the use of DHA-rich fish oil capsules compared with vegetable oil capsules during pregnancy did not result in lower levels of postpartum depression in mothers, or improved cognitive and language development in their offspring during early childhood.
Five Australian maternity hospitals of 2,399 women who were less than 21 weeks' gestation with singleton pregnancies were recruited between Oct. 31, 2005, and Jan. 11, 2008. Follow-up of children (n=726) was completed Dec.16, 2009. Subjects were administered DHA-rich fish oil capsules (providing 800 mg/d of DHA) or matched vegetable oil capsules without DHA from study entry to birth.
Of 2,399 women enrolled, 96.7 percent completed the trial. The percentage of women with high levels of depressive symptoms during the first six months postpartum did not differ between the DHA and control groups. Mean cognitive composite scores and mean language composite scores of children in the DHA group did not differ from children in the control group.
Duffy MacKay, N.D., vice president, scientific & regulatory affairs at CRN, the leading trade association for the dietary supplement industry, commented on the study’s results, stating: “A large body of scientific evidence has established a strong relationship between the DHA status of mothers and infants, and a variety of important pregnancy-related outcomes, including infant development. Unfortunately in this trial, we have no idea of the DHA status of the mothers at the beginning of pregnancy or when they were evaluated for depression. Further, we have no idea of the DHA status of the infants at 18 months when they were evaluated for neurocognitive outcomes. Without measurements of DHA status, it is difficult to draw conclusions from the study and certainly should not provide definitive advice to consumers."
CRN also reminded pregnant and lactating women of the undisputed importance of consuming the recommended amounts of DHA throughout pregnancy via eating two servings of fatty fish, such as sardines or anchovies, per week, or taking fish oil supplements (containing 200 to 300 mg/d of DHA, according to the Institute of Medicine). While the benefits of DHA for a healthy pregnancy are well-established, more research is necessary to determine the effect of DHA on incidence of post-partum depression or neurocognitive development of infants.
Mackay added, ““Supplementation occurred from mid-term to delivery—we know that maternal DHA status returns to below pre-pregnancy levels within a few weeks from delivery. A mother in the treatment group who started the trial with low DHA status would have returned to pre-pregnancy status by the time she was evaluated for depression at six weeks and six months post delivery. We may have seen different results if these women took fish oil consistently leading up to, during and after pregnancy, or if we were able to stratify the results based on DHA status."
