Fish Oil Didn't Help Postpartum Depression



The use of DHA-rich fish oil supplements during pregnancy did not reduce the rate of postpartum depression in mothers or improve neurodevelopment in their children, according to a report.

“Current recommendations suggest that pregnant women increase their dietary DHA [docosahexaenoic acid] to improve their health outcomes as well as those of their children,” and the industry “successfully markets prenatal supplements with DHA to optimize brain function of mother and infant,” noted Maria Makrides, Ph.D., of Women's and Children's Hospital at Flinders Medical Centre in Adelaide, Australia, and her associates.

However, intervention trials with open-label designs, small sample sizes, high attrition rates, or poor statistical power have produced inconclusive results. Dr. Makrides and her colleagues performed the DOMINO (DHA to Optimize Mother Infant Outcome) trial to assess the efficacy and safety of DHA supplements.

In the double-blind trial, 2,320 women with singleton pregnancies who were attending five Australian perinatal centers were randomly assigned to take three fish oil capsules (1,197 women) or placebo capsules containing vegetable oil (1,202 women) daily. The fish oil capsules contained 800 mg/day of DHA and 100 mg/day of eicosapentaenoic acid. The study subjects were enrolled before they reached 21 weeks' gestation and took the supplements until delivery (JAMA 2010;304:1675-83).

The primary maternal outcome was a high level of depressive symptoms during the first 6 months post partum, as assessed by a score of more than 12 on the self-administered Edinburgh Postnatal Depression Scale. The incidence of that outcome was not significantly different between women who took fish oil capsules (9.7%) and the control subjects (11.2%).

In addition, the percentage of women who received a medical diagnosis of depression during the study did not differ significantly between the two groups.

The primary childhood outcome was neurodevelopment at age 18 months, as assessed by scores on the Cognitive and Language Composite Scales of the BSID-III (Bayley Scales of Infant and Toddler Development, third edition). Neither the mean cognitive scores nor the mean language scores differed significantly between children of mothers who took fish oil supplements and children of the control mothers. Similarly, scores on measures of motor development, social-emotional behavior, and adaptive behavior were not significantly different.

The women who took fish oil supplements had a lower rate of very preterm birth (1.1%) compared with the control group (2.3%). However, that was offset by their higher rate of postterm births requiring obstetric intervention (17.6% vs. 13.7%).

Adverse effects, including rates of hemorrhage and antenatal hospitalization, did not differ between the two study groups. The only adverse event that occurred more often in the DHA group than in the controls was eructation.

The Australian National Health and Medical Research Council funded the DOMINO study. Dr. Makrides reported serving on scientific advisory boards for Nestle, Fonterrra, and Nutricia.

DHA-rich fish oil supplements during pregnancy did not reduce the rate of postpartum depression or improve neurodevelopment in children.

Source ©Clayton Hansen/iStockphoto

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A Noteworthy Finding

One noteworthy finding of the DOMINO trial is that women who took fish oil supplements had a significantly lower risk of very preterm birth (defined as delivery before 34 weeks' gestation) than did women in the control group, said Dr. Emily Oken and Dr. Mandy B. Belfort.

The rate of very preterm birth was 1.1% with DHA-rich supplements (13 such births), compared with 2.3% with placebo (27 such births). The downstream benefits of that difference included lower rates of low birth weight, fewer admissions to the neonatal intensive care unit, and a nonsignificant 30% reduction in infant mortality.“

“Although the absolute numbers of these outcomes were small, the relative benefits were large,” they noted.

“For now, pregnant women should take care to get the recommended intake of 200 mg/day of DHA, either by including low-mercury, high-DHA fish in their diets or by taking a daily n-3 PUFA (polyunsaturated fatty acid) supplement. The benefit of higher intakes remains unclear,” Dr. Oken and Dr. Belfort concluded.

DR.OKEN is at Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston. DR. BELFORT is at Children's Hospital Boston. Neither Dr. Oken nor Dr. Belfort reported any financial disclosures. The comments were taken from their editorial accompanying the report (JAMA 2010;304:1717-8).

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