Low omega-3 index in pregnancy is a possible biological risk factor for postpartum depression

Abstract

Background: Depression is a common disorder affecting 10-15% women in the postpartum period. Postpartum depression can disrupt early mother-infant interaction, and constitutes a risk factor for early child development. Recently, attention has been drawn to the hypothesis that a low intake of seafood in pregnancy can be a risk factor for postpartum depression. Seafood is a unique dietary source of the marine omega-3 fatty acids and is a natural part of a healthy balanced diet that is especially important during pregnancy.

Methods: In a community based prospective cohort in a municipality in Western Norway, we investigated both nutritional and psychological risk factors for postpartum depression. The source population was all women who were pregnant within the period November 2009 - June 2011. The fatty acid status in red blood cells was assessed in the 28(th) gestation week and participants were screened for postpartum depression using the Edinburgh Postnatal Depression Scale (EPDS) three months after delivery. The aim of the present study was to investigate if a low omega-3 index in pregnancy is a possible risk factor for postpartum depression.

Results: In a simple regression model, the omega-3 index was associated with the EPDS score in a nonlinear inverse manner with an R square of 19. Thus, the low omega-3 index explained 19% of the variance in the EPDS score. The DPA content, DHA content, omega-3 index, omega-3/omega-6 ratio, total HUFA score, and the omega-3 HUFA score were all inversely correlated with the EPDS score. The EPDS scores of participants in the lowest omega-3 index quartile were significantly different to the three other omega-3 index quartiles.

Conclusion: In this study population, a low omega-3 index in late pregnancy was associated with higher depression score three months postpartum.

Figure 1. Flow chart of the study design.

* Of which one respondent did not provide a blood sample ** Of which 54 responders and 15 non-responders to the electronic questionnaire *** Of which 35 responders and 8 non-responders to the electronic questionnaire. 26 participants were not screened for depression 3 months postpartum due to drop out or losses to follow up.

Figure 2. Association between the omega-3 index in pregnancy and postpartum depression.

Scatter plot of the non-linear relationship between the marine omega-3 status (omega-3 index) in pregnancy and postpartum depression score (EPDS). A rectangular hyperbolic equation (y = -1.31+28.1/x) was the best fit for describing this relationship (ß = 0.43, F (1,41) = 9.32, p<0.004, n = 43). The vertical lines represent omega-3 index quartiles. Red markers represent individuals in the 25 percentile. † The content of EPA+DHA in red blood cells membranes expressed as a percent of total fatty acids ‡ Edinburgh postnatal depression scale.

Figure 3. Association between the omega-3 index and absolute DHA and EPA in red blood cells.

Scatter plot of the omega-3 index and the corresponding DHA content (µg/g) and EPA content (µg/g) in red blood cells, and the respective fitted regression lines. The omega-3 index is the content of EPA+DHA in red blood cells membranes expressed as a percent of total fatty acids.

Figure 4. Participant’s response to the electronic questionnaire in pregnancy.

Bar chart presenting the median EPDS score measured 3 months postpartum of non-responders (n = 8) and responders (n = 36) to an electronic questionnaire (seafood intake, demography, socioeconomically status, psychological status) in pregnancy. * Significantly difference at the 0.001 level. † 28th week gestation. ‡ Edinburgh postnatal depression scale.

Figure 5. Seafood consumption and prevalence rates of postpartum depression.

Postpartum prevalence rates for Australia, New Zealand, Sweden and the United Kingdom, The United States were derived by meta-analysis. All other countries are represented by a single study, see text. Apparent Seafood consumption lb/person/year is an economic measure of disappearance of all fish and seafood from the economy and is calculated by imports plus catch minus exports. A logarithmic regression was used for analysis (r = −0.81, p<0.001). In Norway the seafood consumption is (47 lbs/person/year = 21,3 kg/person/year and the prevalence of postpartum depression is 10% . Modified from Hibbeln et al. .