Background & Objectives: Postpartum depression is one of the most important problems during post partum. Several new medications have been introduced for treatment, but considering their side effects and also breast feeding women's desire for dietary complements rather than chemical drugs, this research was done to determine comparison of effectiveness of Omega-3 fatty acids with placebo in treatment of mild to moderate postpartum depression.

  Methods: This double-blind randomized placebo controlled trial study was done on 120 women with postpartum depression, who had the required criteria. First by using Edinburgh Postnatal Depression Scale (EPDS) in women who gave birth 2 weeks to 3 months before, postpartum depression approved for determining the severity of depression, Beck Depression Inventory scale (BDI) was used. Women with mild to moderate depression who had a score 46 on the (BDI) and did not have any tendency to use anti-depressant drugs under the supervision of the psychiatrist, enrolled in the study and randomly assigned to receive either 1gr of Omega-3 capsules or placebo for 8 weeks. Severity of depression was measured before treatment and weekly during treatment in both groups. The data analyzed through T-Test, repeated measurements of one way ANOVA and chi square test in SPSS 14/Win.

  Results: There were no significant differences between two groups with respect to demographic characteristics. Results show that Mean Depression Scores before treatment in Omega-3 group (35.4 ± 9.2) decreased after treatment (17.7 ± 7.0), which was significant (p<0.0005). Mean Depression Scores before treatment in placebo group (34.2 ± 3.4) decreased after treatment (33.6 ± 9.3) which wasn't significant (p=0.57). There was a significant difference between reductions of Depression Scores in two groups(P<0.001).

  Conclusion: According to research results, use of Omega-3 1gr/day for 8 weeks improves postpartum depression.