Omega-3 supplementation from pregnancy to postpartum to prevent depressive symptoms: a randomized placebo-controlled trial

Double-blind, randomized, placebo-controlled trial nested within an observational cohort conducted in Rio de Janeiro, Brazil. Participants: 60 pregnant women at risk for postpartum depression (history of depression or Edinburgh Postnatal Depression Scale baseline >=9), aged 20-40, without major chronic diseases; randomly assigned to fish oil or placebo.

Six 1-g gelatin capsules daily totaling 1.8 g of n-3 polyunsaturated fatty acids (1.08 g EPA and 0.72 g DHA) per day, taken as three capsules at lunch and three capsules at dinner, started at 22-24 weeks of gestation and continued for 16 weeks.

In intention-to-treat analysis, there were no differences between groups in the prevalence of depressive symptoms (EPDS score >=11) across pregnancy and postpartum, nor in EPDS scores over time or changes from pregnancy to postpartum. By 30-32 weeks gestation, fish oil raised total n-3, EPA and DHA serum levels and lowered the n-6/n-3 ratio compared with controls. Among women with a prior history of depression, fish oil was associated with a greater reduction in EPDS score from the second trimester to postpartum (beta = -3.441; 95% CI: -6.532 to -0.350; p = 0.029) and this finding was supported by the longitudinal model. Gestational length and birth weight did not differ between groups. Conclusion: Daily supplementation of 1.8 g/day of n-3 PUFAs from the second trimester for 16 weeks did not prevent maternal depressive symptoms in this Brazilian at-risk population; potential benefit may exist for women with prior depression and requires further study.

Small sample size with substantial attrition (32 completed of 60 randomized); limited postpartum follow-up (4-6 weeks); results may not generalize to broader populations; outcomes largely based on EPDS screening rather than clinical diagnosis.