BACKGROUND: Mothers may be reluctant to receive medical treatment of postpartum depression (PPD), despite the detrimental consequences the disorder can impose on mother and child. Research on alternative methods of prevention and treatment of PPD is warranted. Previous studies have suggested that long-chain n-3 polyunsaturated fatty acids (PUFAs) might have a beneficial effect on depression.

OBJECTIVE: The objective was to explore the association between intake of fish and n-3 PUFAs during pregnancy and PPD in the Danish National Birth Cohort (DNBC). DESIGN: Exposure information from the DNBC was linked to the Danish patient and prescription registries for data on clinically identified cases of depression up to 1 y postpartum. Intake of fish and n-3 PUFAs was assessed in midpregnancy with a food-frequency questionnaire. Admission to the hospital for PPD (PPD-admission) and prescription of antidepressants (PPD-prescription) were treated as separate outcomes. A total of 54,202 women were included in the present study sample.

RESULTS: Rates of depression were 0.3% (PPD-admission) and 1.6% (PPD-prescription). No association was observed between fish intake and risk of PPD-admission [crude odds ratio of 1.01 (95% CI: 0.52, 1.97) and adjusted odds ratio of 0.82 (95% CI: 0.42, 1.64)], whereas a higher risk of PPD-prescription was found for the lowest compared with the highest fish intake group [crude odds ratio of 1.61 (95% CI: 1.26, 2.06) and adjusted odds ratio of 1.46 (95% CI: 1.12, 1.90)]. No association was observed with respect to n-3 PUFA intake.

CONCLUSION: Overall, our data from a large prospective cohort linked with high-quality registers showed little evidence to support an association between intake of fish or n-3 PUFAs and PPD.