Maternal deficiency of the omega-3 fatty acid, docosahexaenoic acid (DHA), has been associated with perinatal depression, but there is evidence that supplementation with eicosapentaenoic acid (EPA) may be more effective than DHA in treating depressive symptoms. This trial tested the relative effects of EPA- and DHA-rich fish oils on prevention of depressive symptoms among pregnant women at an increased risk of depression.

We enrolled 126 pregnant women at risk for depression (Edinburgh Postnatal Depression Scale score 9-19 or a history of depression) in early pregnancy and randomly assigned them to receive EPA-rich fish oil (1060 mg EPA plus 274 mg DHA), DHA-rich fish oil (900 mg DHA plus 180 mg EPA), or soy oil placebo. Subjects completed the Beck Depression Inventory (BDI) and Mini-International Neuropsychiatric Interview at enrollment, 26-28 weeks, 34-36 weeks, and at 6-8 weeks' postpartum. Serum fatty acids were analyzed at entry and at 34-36 weeks' gestation.

One hundred eighteen women completed the trial. There were no differences between groups in BDI scores or other depression endpoints at any of the 3 time points after supplementation. The EPA- and DHA-rich fish oil groups exhibited significantly increased postsupplementation concentrations of serum EPA and serum DHA respectively. Serum DHA- concentrations at 34-36 weeks were inversely related to BDI scores in late pregnancy.

EPA-rich fish oil and DHA-rich fish oil supplementation did not prevent depressive symptoms during pregnancy or postpartum.