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Higher n-3 polyunsaturated fatty acid status during early pregnancy is associated with lower risk for depression at 12 months postpartum: The NuPED study

Open AccessPublished:January 13, 2023DOI:https://doi.org/10.1016/j.plefa.2022.102528

      Highlights

      • Higher red blood cell (RBC) DHA and n-3 index were associated with lower odds for depression at 12 months postpartum.
      • Higher n-6/n-3 PUFA and AA/EPA ratios at early pregnancy were associated with higher odds for depression at 12 months postpartum.
      • Women with higher RBC n-3 PUFA status during early pregnancy may be at lower risk for depression at 12 months postpartum.

      Abstract

      Perinatal depression can negatively affect the health of the mother and her offspring. N-3 polyunsaturated fatty acids (PUFA) may play a role in the aetiology of depression. Therefore, we investigated the association of n-3 PUFA status during early pregnancy with perinatal depression among women living in urban Johannesburg, South Africa. For this prospective analysis, we analysed red blood cell (RBC) total phospholipid fatty acid (FA) composition (% of total FA) of 242 pregnant women at <18 weeks’ gestation. We used the Edinburgh Postnatal Depression Scale (EPDS) to identify women at risk for depression (EPDS score 9) at <18, 22 and 36 weeks’ gestation, and at 6 and 12 months postpartum. RBC EPA status was negatively (β=-0.22, p<0.05), and the AA/EPA ratio positively (β=0.24, p<0.05) associated with EPDS scores at 12 months postpartum. Higher RBC DHA and n-3 index were further associated with lower odds (OR=0.56 [95% CI: 0.32-0.91]; OR=0.63 [95% CI: 0.39-0.94]), while higher n-6/n-3 PUFA and AA/EPA ratios early in pregnancy were associated with higher odds for depression at 12 months postpartum ((OR=2.34 [95% CI: 1.12-4.97]; OR=1.02 [95% CI: 1.00-1.05]). Our results suggest that women with a higher RBC n-3 PUFA status during early pregnancy may be at lower risk for depression at 12 months postpartum.

      Keywords

      1. Introduction

      Perinatal depression refers to major and minor depressive episodes during pregnancy (prenatally) and the first year after delivery (postnatally) [
      • Alhusen J.L.
      • Alvarez C.
      Perinatal depression: a clinical update.
      ]. Estimated prevalence rates for perinatal depression in high-income countries (HIC) are approximately 9% [
      • Woody C.A.
      • Ferrari A.J.
      • Siskind D.J.
      • Whiteford H.A.
      • Harris M.G.
      A systematic review and meta-regression of the prevalence and incidence of perinatal depression.
      ]. In contrast, estimated prevalence rates in low- and middle-income countries (LMIC) reach up to 50% [
      • Alhusen J.L.
      • Alvarez C.
      Perinatal depression: a clinical update.
      ,
      • Woody C.A.
      • Ferrari A.J.
      • Siskind D.J.
      • Whiteford H.A.
      • Harris M.G.
      A systematic review and meta-regression of the prevalence and incidence of perinatal depression.
      ,
      • Parsons C.E.
      • Young K.S.
      • Rochat T.J.
      • Kringelbach M.L.
      • Stein A.
      Postnatal depression and its effects on child development: a review of evidence from low- and middle-income countries.
      ]. Perinatal depression may result in women finding it difficult to perform everyday tasks, failure to seek perinatal care, poor dietary intake, and self-harm or suicide [
      • Lin P.-Y.
      • Chang C.-H.
      • Chong M.F.-F.
      • Chen H.
      • Su K.-P.
      Polyunsaturated fatty acids in perinatal depression: a systematic review and meta-analysis.
      ,
      • Miller B.
      • Murray L.
      • Beckmann M.
      • Kent T.
      • Macfarlane B.
      Dietary supplements for preventing postnatal depression (Review).
      ]. Furthermore, perinatal depression has been associated with poorer childhood outcomes such as behavioural problems, attentional deficits and impaired cognitive function [
      • Parsons C.E.
      • Young K.S.
      • Rochat T.J.
      • Kringelbach M.L.
      • Stein A.
      Postnatal depression and its effects on child development: a review of evidence from low- and middle-income countries.
      ,
      • Gelaye B.
      • Rondon M.B.
      • Araya R.
      • Williams M.A.
      Epidemiology of maternal depression, risk factors, and child outcomes in low-income and middle-income countries.
      ,
      • Voortman T.
      • Tielemans M.J.
      • Stroobant W.
      • Schoufour J.D.
      • Kiefte-de Jong J.C.
      • Steenweg-de Graaff J.
      • van den Hooven E.H.
      • Tiemeier H.
      • Jaddoe V.W.
      • Franco O.H.
      Plasma fatty acid patterns during pregnancy and child’s growth, body composition, and cardiometabolic health: the generation R study.
      ,
      • Wachs T.D.
      • Black M.M.
      • Engle P.L.
      Maternal depression: a global threat to children’s health, development, and behavior and to human rights.
      ,
      • Zou R.
      • Tiemeier H.
      • van der Ende J.
      • Verhulst F.C.
      • Muetzel R.L.
      • White T.
      • Hillegers M.
      • El Marroun H.
      Exposure to maternal depressive symptoms in fetal life or childhood and offspring brain development: a population-based imaging study.
      ]. Thus, perinatal depression can have serious health implications for both the mother and her child.
      Even though the aetiology of depressive disorders remains unclear, it is likely multifactorial. There is a growing body of research indicating a link between depressive symptoms and modifiable nutritional risk factors, especially poor n-3 polyunsaturated fatty acid (PUFA) status [
      • Lin P.-Y.
      • Chang C.-H.
      • Chong M.F.-F.
      • Chen H.
      • Su K.-P.
      Polyunsaturated fatty acids in perinatal depression: a systematic review and meta-analysis.
      ,
      • Hoge A.
      • Tabar V.
      • Donneau A.F.
      • Dardenne N.
      • Degée S.
      • Timmermans M.
      • Nisolle M.
      • Guillaume M.
      • Castronovo V.
      • Hoge
      • Tabar
      • Donneau
      • Dardenne
      • Degée
      • Timmermans
      • Nisolle
      • Guillaume
      • Castronovo
      Imbalance between omega-6 and omega-3 polyunsaturated fatty acids in early pregnancy is predictive of postpartum depression in a Belgian cohort.
      ,
      • Levant B.
      N-3 (omega-3) fatty acids in postpartum depression: implications for prevention and treatment.
      ,
      • Markhus M.W.
      • Skotheim S.
      • Graff I.E.
      • Froyland L.
      • Braarud H.C.
      • Stormark K.M.
      • Malde M.K.
      Low omega-3 index in pregnancy is a possible biological risk factor for postpartum depression.
      ,
      • Marx W.
      • Lane M.
      • Hockey M.
      • Aslam H.
      • Berk M.
      • Walder K.
      • Borsini A.
      • Firth J.
      • Pariante C.M.
      • Berding K.
      • Cryan J.F.
      • Clarke G.
      • Craig J.M.
      • Su K.P.
      • Mischoulon D.
      • Gomez-Pinilla F.
      • Foster J.A.
      • Cani P.D.
      • Thuret S.
      • Staudacher H.M.
      • Sánchez-Villegas A.
      • Arshad H.
      • Akbaraly T.
      • O’Neil A.
      • Segasby T.
      • Jacka F.N.
      Diet and depression: exploring the biological mechanisms of action.
      ,
      • Pinto T.J.
      • Vilela A.A.
      • Farias D.R.
      • Lepsch J.
      • Cunha G.M.
      • Vaz J.S.
      • Factor-Litvak P.
      • Kac G.
      Serum n-3 polyunsaturated fatty acids are inversely associated with longitudinal changes in depressive symptoms during pregnancy.
      ]. Some of the putative mechanisms underlying the observed associations between n-3 PUFA status and mental health involve their role in neurogenesis and neuroplasticity, the tryptophan-kynurenine metabolism and the gut-microbiota-brain axis [
      • Marx W.
      • Lane M.
      • Hockey M.
      • Aslam H.
      • Berk M.
      • Walder K.
      • Borsini A.
      • Firth J.
      • Pariante C.M.
      • Berding K.
      • Cryan J.F.
      • Clarke G.
      • Craig J.M.
      • Su K.P.
      • Mischoulon D.
      • Gomez-Pinilla F.
      • Foster J.A.
      • Cani P.D.
      • Thuret S.
      • Staudacher H.M.
      • Sánchez-Villegas A.
      • Arshad H.
      • Akbaraly T.
      • O’Neil A.
      • Segasby T.
      • Jacka F.N.
      Diet and depression: exploring the biological mechanisms of action.
      ]. Furthermore, inflammatory processes may play a major role in the development of depression [
      • Beurel E.
      • Toups M.
      • Nemeroff C.B.
      The bidirectional relationship of depression and inflammation: double trouble.
      ,
      • Dantzer R.
      • O’Connor J.C.
      • Freund G.G.
      • Johnson R.W.
      • Kelley K.W.
      From inflammation to sickness and depression: when the immune system subjugates the brain.
      ,
      • Lee C.H.
      • Giuliani F.
      The role of inflammation in depression and fatigue.
      ]. The n-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are precursors for the production of anti-inflammatory and inflammation-resolving mediators [
      • Calder P.C.
      N-3 fatty acids, inflammation and immunity: new mechanisms to explain old actions.
      ]. A low n-3 PUFA status might be particularly detrimental during the perinatal period when women are at increased risk of depression relapse or newly diagnosed depression. However, data on the associations between maternal n-3 PUFA status and perinatal depression are limited and inconsistent [
      • Lin P.-Y.
      • Chang C.-H.
      • Chong M.F.-F.
      • Chen H.
      • Su K.-P.
      Polyunsaturated fatty acids in perinatal depression: a systematic review and meta-analysis.
      ,
      • Hsu M.C.
      • Tung C.Y.
      • Chen H.E.
      Omega-3 polyunsaturated fatty acid supplementation in prevention and treatment of maternal depression: putative mechanism and recommendation.
      ,
      • Trujillo J.
      • Vieira M.C.
      • Lepsch J.
      • Rebelo F.
      • Poston L.
      • Pasupathy D.
      • Kac G.
      A systematic review of the associations between maternal nutritional biomarkers and depression and/or anxiety during pregnancy and postpartum.
      ].
      The n-3 PUFA status of an individual can be assessed by measuring the fatty acid (FA) composition of red blood cell (RBC) membranes and expressed either as individual n-3 PUFA (in percentage of total FA) or as the sum of EPA + DHA (also called the "omega (n)-3 index"). Globally, low and very low levels of n-3 PUFA status (n-3 index 6% and 4%, respectively) have been observed in many high-income populations, while data from LMIC are still scarce [
      • Stark K.D.
      • Van Elswyk M.E.
      • Higgins M.R.
      • Weatherford C.A.
      • Salem N.
      Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults.
      ]. Factors such as diet, supplementation, sex, age, and body-mass-index (BMI) have been associated with n-3 PUFA status [
      • De Groot R.H.
      • Emmett R.
      • Meyer B.J.
      Non-dietary factors associated with n-3 long-chain PUFA levels in humans - a systematic literature review.
      ,
      • Harris W.S.
      • Pottala J.V.
      • Lacey S.M.
      • Vasan R.S.
      • Larson M.G.
      • Robins S.J.
      Clinical correlates and heritability of erythrocyte eicosapentaenoic and docosahexaenoic acid content in the Framingham Heart Study.
      ]. Low conversion rates of the essential n-3 PUFA precursor alpha-linolenic acid (ALA) to EPA and DHA contribute to a low n-3 PUFA status in populations with a low intake of preformed EPA and DHA, e.g. from fish or supplements. Conversion rates can be further affected by variations in genes coding for desaturase and elongase enzymes. During pregnancy and lactation, requirements of n-3 PUFA are increased because the supply to the foetus mainly depends on the mother’s intake [
      • Carlson S.E.
      • Colombo J.
      • Gajewski B.J.
      • Gustafson K.M.
      • Mundy D.
      • Yeast J.
      • Georgieff M.K.
      • Markley L.A.
      • Kerling E.H.
      • Shaddy D.J.
      DHA supplementation and pregnancy outcomes.
      ,
      • Hornstra G.
      Essential fatty acids in mothers and their neonates.
      ]. Therefore, pregnant and lactating women are at increased risk of inadequate n-3 PUFA intake and status compared to other population groups.
      In South Africa, the estimated prevalence of postnatal depression is around 20-30% [
      • Parsons C.E.
      • Young K.S.
      • Rochat T.J.
      • Kringelbach M.L.
      • Stein A.
      Postnatal depression and its effects on child development: a review of evidence from low- and middle-income countries.
      ]. The nutritional status of pregnant women in South Africa is poorly described. However, a previous South African study in women of reproductive age indicated that the intake of n-3 PUFA is below recommendations in both rural and urban areas [
      • Ford R.
      • Faber M.
      • Kunneke E.
      • Smuts C.M.
      Dietary fat intake and red blood cell fatty acid composition of children and women from three different geographical areas in South Africa.
      ]. Therefore, the aim of this study was to investigate the association of n-3 PUFA status during early pregnancy with perinatal depression among women living in urban Johannesburg, South Africa. Thereby, we described the n-3 PUFA status as single RBC n-3 PUFA, the n-3 index, and the n-6/n-3 PUFA ratio. We further determined RBC FA patterns by Principal Component Analysis (PCA) to overcome the limitations of other n-3 PUFA status indicators not considering the mutual dependence of FA and the influence of change in proportion of one FA on the rest of the FA in RBC membranes.

      2. Methods and materials

      2.1 Study design and participants

      This study formed part of the Nutrition during Pregnancy and Early Development (NuPED) study, a prospective cohort study conducted in Johannesburg, South Africa. The NuPED protocol has been published previously [
      • Symington E.A.
      • Baumgartner J.
      • Malan L.
      • Zandberg L.
      • Ricci C.
      • Smuts C.M.
      Nutrition during pregnancy and early development (NuPED) in urban South Africa: a study protocol for a prospective cohort.
      ]. The NuPED study was approved by the Health Research Ethics Committee (HREC) of the North-West University (NWU), South Africa (NWU-00186-15-A1 and NWU-00049-16-A1) as well as the University of Witwatersrand, Johannesburg (M150968 and M161045). In brief, generally healthy pregnant women were recruited from primary healthcare clinics in Johannesburg between March 2016 and November 2017. The women were followed throughout pregnancy to birth and up to 12 months postpartum at Rahima Moosa Mother and Child Hospital (RMMCH) in Johannesburg, South Africa until June 2018. Data were collected at early pregnancy (<18 weeks of gestation), mid-pregnancy (±22 weeks), late pregnancy (±36 weeks), and at 6 weeks, 6 months, and 12 months postpartum.
      Women were eligible for inclusion if they were aged 18-39 years, <18 weeks of gestation with singleton pregnancies, proficient in local languages, born in South Africa or neighbouring countries, and if they have been residing in Johannesburg for at least 12 months. Women were excluded if they reported using illicit drugs, were smoking, or had been diagnosed with a non-communicable disease such as diabetes, renal disease, high cholesterol, and hypertension; an infectious disease such as tuberculosis and hepatitis; or a serious illness such as cancer, lupus or psychosis. Due to South Africa’s high prevalence of HIV infection (36%) [
      • Shisana O.
      • Rehle T.
      • Simbayi L.
      • Zuma K.
      • Jooste S.
      • Zungu N.
      • Labadarios D.
      • Onoya D.
      South African National HIV Prevalence, Incidence and Behaviour Survey, 2012.
      ], women living with HIV were included in the study to be a better representation of the general South African population.

      2.2 Outcome measurements

      The primary outcome measure was perinatal depression at six time points: early pregnancy (<18 weeks of gestation), mid-pregnancy (±22 weeks), late pregnancy (±36 weeks), and at 6 weeks, 6 months, and 12 months postpartum. Depression was assessed using the interviewer-administered Edinburgh Postnatal Depression Scale (EPDS). The EPDS is a 10-item scale assessing depressive symptoms experienced in the past 7 days [
      • Cox J.L.
      • Holden J.M.
      • Sagovsky R.
      Detection of postnatal depression: development of the 10-item edinburgh postnatal depression scale.
      ], which has been validated for assessing perinatal depression in African settings, including South Africa [
      • Tsai A.C.
      • Scott J.A.
      • Hung K.J.
      • Zhu J.Q.
      • Matthews L.T.
      • Psaros C.
      • Tomlinson M.
      Reliability and validity of instruments for assessing perinatal depression in african settings: systematic review and meta-analysis.
      ]. To classify women as being at risk of depression, we used an EPDS cut-off score of 9 (out of a maximum score of 30), which was shown to have a high sensitivity for detecting perinatal depression in African contexts [
      • Tsai A.C.
      • Scott J.A.
      • Hung K.J.
      • Zhu J.Q.
      • Matthews L.T.
      • Psaros C.
      • Tomlinson M.
      Reliability and validity of instruments for assessing perinatal depression in african settings: systematic review and meta-analysis.
      ].

      2.3 Exposure measurements

      The primary exposure measure was maternal n-3 PUFA status assessed at <18 weeks of gestation by analysing the FA composition of RBC total phospholipids and expressed as single FA (ALA, DHA and EPA), the n-6/n-3 PUFA ratio, and the n-3 index. Further exposure variables were RBC FA patterns derived by conducting principal component analysis (PCA).
      Maternal venous blood for the analysis of RBC FA composition was drawn into EDTA-coated evacuated tubes (Vacuette®, Greiner Bio-One) and was processed within 1 h. During processing, RBC were separated from plasma by centrifugation at 2000 g for 10 min and were washed twice with normal saline solution. Aliquots were stored on site at -20°C for a maximum of 14 days until transportation for final storage at -80C until analysis.
      RBC total phospholipids FA analysis was carried out at the North-West University Centre of Excellence for Nutrition using Gas Chromatography-Mass Spectrometry (GC-MS) as described previously [
      • Baumgartner J.
      • Smuts C.M.
      • Malan L.
      • Kvalsvig J.
      • Van Stuijvenberg M.E.
      • Hurrell R.F.
      • Zimmermann M.B.
      Effects of iron and n-3 fatty acid supplementation, alone and in combination, on cognition in school children: a randomized, double-blind, placebo-controlled intervention in South Africa.
      ]. Lipids were extracted from RBC samples with chloroform: methanol (2:1, vol:vol) by using a modification of the method of Folch [
      • Folch J.
      • Lees M.
      • Sloane Stanley G.H.
      A simple method for the isolation and purification of total lipides from animal tissues.
      ]. Lipid extracts were concentrated using nitrogen gas, and thin-layer chromatography (silica gel 60 plates without fluorescent indicator, 10 x 20 cm; Merck) was used to separate neutral lipids from the phospholipids. Phospholipids were eluted using petroleum ether: diethyl ether (peroxide free): acetic acid (90:30:1, vol:vol:vol) and a pinch of UV fluorescent indicator 2.5-Bis(5-tert-butyl-benzoxazol-2-yl) thiophene. The lipid fraction containing the phospholipids was visualized under long-wave UV light, removed from the thin-layer chromatography plate and trans-methylated with methanol: sulphuric acid (95:5, vol:vol) at 70C for 2 h. This led to the formation of fatty acid methyl esters (FAME). The FAME were extracted using hexane and water. The organic layer was aspirated, evaporated, redissolved in hexane, and analysed by gas chromatography-electron ionisation mass spectrometry. All solvents used during the extraction procedure contained 0.01% butylated hydroxytoluene. Samples were analysed on an Agilent Technologies 7000 GC/MS Triple quad system comprising an Agilent 7890A gas chromatograph equipped with an Agilent G7001B triple quad mass spectrometer (Agilent Technologies). The gas chromatography separation of FAME was carried out on an HP-88 capillary column (100m x 0.25 mm x 0.20 μm; Agilent Technologies) by using helium as the carrier gas at a flow rate of 2.2 mL/min. Initial inlet temperature was held at 70C for 0.02 min, after which it was ramped to 270C at 500C/min. The mass spectrometer source was maintained at a temperature of 230C. A sample volume of 1 μL was injected and a split ratio of 80:1 for RBC samples was used. The oven temperature was maintained at 50C for 1 min, then ramped to 170C at 30C/min, then from 170C to 215C at 2C/min, after which it was ramped to 230C at 4C/min. The temperature was then held isothermally at 230C for 7 min. The total analysis time was 38.25 min. Mass spectrometry with 70 eV electron-ionisation was carried out in multiple-reaction monitoring mode, with at least two transitions per compound. The FAME were quantified using MassHunter Quantitative Analysis software (Version B.05.02, Agilent Technologies). FAME peaks were identified and calibrated against a standard reference mixture of 33 FAME (Nu-Check-Prep) and two single FAME standards (Larodan Fine Chemicals AB). Relative percentages of FAs were calculated by expressing the concentration of a given FAME as a percentage of the total concentration of all FAME identified in the sample [
      • Baumgartner J.
      • Smuts C.M.
      • Malan L.
      • Kvalsvig J.
      • Van Stuijvenberg M.E.
      • Hurrell R.F.
      • Zimmermann M.B.
      Effects of iron and n-3 fatty acid supplementation, alone and in combination, on cognition in school children: a randomized, double-blind, placebo-controlled intervention in South Africa.
      ].

      2.4 Covariates

      All the covariates were assessed at the first visit (<18 weeks gestation).
      Maternal socio-economic and -demographic data were collected during a structured interview, and included date and country of birth, marital status, ethnicity, educational level, and living standards measure (LSM) scores. The LSM score was developed by the South African Audience Reference Foundation (SAARF) and is widely used in South Africa to describe the socio-economic status of the population [
      • Labadarios D.
      • Steyn N.P.
      • Nel J.
      How diverse is the diet of adult South Africans?.
      ,

      South African Audience Research Foundation, Living Standards Measure, 2017. http://saarf.co.za/LSM/lsms.asp.

      ].
      Anthropometric measurements, such as height and weight, were obtained using standardised methods from the International Society for the Advancement of Kinanthropometry [

      M.J. Marfell-Jones, A.D. Stewart, J.H. de Ridder, International standards for anthropometric assessment. (2012). https://repository.openpolytechnic.ac.nz/handle/11072/1510.

      ]. All measurements were conducted twice and recorded to the nearest 0.05 kg of weight and 0.1 cm for height.
      Medical files were inspected to obtain data on maternal HIV status and sex of the baby. During analyses, women were considered HIV positive irrespective of date of HIV contraction (prior to or during pregnancy).

      2.5 Statistical methods

      Data were tested for outliers and normality by means of Q-Q plots, histograms and Shapiro-Wilk test. Outliers were inspected and checked for unrealistic values, typing errors, and quantitation errors. Normally distributed data and non-normally distributed data were expressed as mean (±SD) and as medians (interquartile range (IQR)), respectively. We used multivariate linear regression analysis to assess associations of different FA status indicators with EPDS scores as continuous outcome variable, and logistic regression analysis to assess associations of FA status indicators with perinatal depression defined as EPDS score 9 (dichotomous variable). Thereby we applied two models: In the basic model 1, age of the mother and gestational age were included as covariates; in model 2, age of the mother, gestational age, BMI, HIV status, and the LSM score were included as covariates. All statistical tests were two tailed and type-I error rate was set at α =0.05. Raw data were captured in Microsoft Access (Microsoft Corporation, Washington, USA) and 20% of all captured data were randomly checked for correctness. Data processing and statistical analysis of data were performed using R Version 3.6.0 [

      R.F.f. S. C. R Core Team, R: a language and environment for statistical computing, 2013. http://www.r-project.org/.

      ]. R packages used for PCA were: ‘corpcor’, ‘GPA rotation’, ‘psych’.
      A factor analysis based on PCA of the correlation matrix with orthogonal rotation (varimax) was conducted on the 29 phospholipid FA to explore maternal FA patterns. To correct for skewness, we applied a Blom transformation on the data [
      • Blom G.
      Statistical Estimates and Transformed Beta-Variables.
      ]. The Kaiser-Meyer-Olkin (KMO) measure verified the sampling adequacy for the analysis (KMO = 0.62; ’mediocre’ according to Kaiser, 1974 [
      • Field A.
      • Miles J.
      • Field Z.
      Discovering Statistics using R.
      ]), and all KMO values for individual variables were >0.3. An initial analysis was run to obtain eigenvalues for each component in the data. Four components had eigenvalues over Kaiser’s criterion of 1 and in combination explained 46.9% of the variance. The scree plot was slightly ambiguous and showed inflexions that would justify retaining both four and five components. Given the convergence of the scree plot and Kaiser’s criterion on four components, four components were retained in the final analysis. Factor loadings describing the strength of individual FA contributing to each FA pattern are presented in Table 3. On the basis of high factor loadings (|0.40|) for the respective fatty acids (Table 3), we named these patterns: 1) ‘high saturated FA’ pattern; 2) ‘Low DHA and n-6 PUFA, and high trans FA’ pattern; 3) ‘high ALA, EPA, n-3 DPA and n-6 DGLA’; and 4) ‘high n-3 PUFA’ pattern. Each pregnant woman had an individual score on each of the four components, so called FA patterns. These individual scores were used in the logistic and linear regression models (as continuous variables).

      3. Results

      3.1 Participant characteristics

      A flow-chart of the pregnant women included and followed-up in the NuPED study and the availability of data for analysis in this study is shown in Fig. 1. A total of 250 women were enrolled into the NuPED study, but FA data were available for 242 women only and therefore included in the analysis. Of these, EPDS data were available from 238, 224, 191, 50, 84, and 89 women at enrolment, mid-pregnancy (±22 weeks), late pregnancy (±36 weeks), and at 6 weeks, 6 months, and 12 months postpartum, respectively.
      Fig. 1
      Fig. 1Flow-chart of pregnant women included in the NuPED study and in the prospective analysis of this study (boxes in bold). EPDS: Edinburgh Postnatal Depression Scale; IUFD: Intrauterine foetal death; RMMCH: Rahima Moosa Mother and Child Hospital.
      Baseline characteristics of study participants are presented in Table 1. We found a median age of 28 years and a median (IQR) BMI of 26.5 (12.1, 16.1) kg/m2. Most study participants lived in medium living standards according to the LSM. Finally, around one quarter of study participants were HIV positive.
      Table 1Characteristics of the pregnant women at enrolment (<18 weeks of gestation).
      Maternal characteristicsn
      Age (years)24228.0 (24.0, 32.0)
      Gestational age (weeks)24214.3 (12.1, 16.1)
      BMI (km/m2)24126.5 (23.2, 30.7)
      Underweight (<18.5 km/m2)8 (3)
      Normal weight (18.5-24.9 km/m2)82 (34)
      Overweight (25-29.9 km/m2)81 (34)
      Obese (30 km/m2)70 (29)
      Ethnicity241
      Black African211 (87)
      Mixed ancestry28 (12)
      Indian1 (0.4)
      White1 (0.4)
      Country of birth233
      South Africa169 (70)
      Zimbabwe57 (24)
      Lesotho4 (2)
      Swaziland3 (1)
      Living Standards Measure (LSM)2427.0 (6.0, 8.0)
      Low (LSM 1-4)17 (7)
      Medium (LSM 5-7)141 (58)
      High (LSM 8-10)84 (35)
      Maritial Status241
      Unmarried / single96 (40)
      Married67 (30)
      Living together55 (23)
      Traditional marriage21 (9)
      Divorced/Separated2 (1)
      Highest level of education241
      Primary school or less7 (3)
      Grade 8-1037 (15)
      Grade 11-12140 (58)
      Tertiary post school education57 (24)
      Parity242
      Nulliparous69 (29)
      Primiparous86 (36)
      Biparous67 (28)
      Multiparous20 (8)
      HIV status242
      Negative179 (74)
      Positive63 (26)
      EPDS score2385(2, 8)
      EPDS score <9179 (74)
      EPDS score 959 (24)
      Inflammatory status242
      No inflammation (CRP <5mg/L; AGP <1g/L)92 (38)
      Inflammation (CRP >5mg/L and/or AGP >1g/L)150 (62)
      Values are displayed as median (interquartile range) for continuous variables and n (%) for categorical variables. AGP: alpha-1 glycoprotein; BMI: body mass index; CRP: C-reactive protein; EPDS: Edinburgh Postnatal Depression Scale

      3.2 Perinatal depression prevalence

      Fig. 2 shows the prevalence of having an EPDS score indicative for perinatal depression (cut-off 9) in the women at the pre- and postnatal follow-ups. The prevalence rates ranged from 17% to 26%, with the highest prevalence at 6 months postpartum (26%) and the lowest prevalence at ±36 weeks of gestation (17%). The median (IQR) EPDS scores were 5 (2, 8) at <18 weeks gestation, 3 (1, 6) at 22 weeks gestation, 3 (0, 6) at 36 weeks gestation, 4.5 (0.25, 7.75) at 6 weeks postpartum, 5 (2, 9) at 6 months postpartum, and 4 (1, 8) at 12 months postpartum. We did not find a significant difference in the medians between the pre- and post-delivery visits. Only 4% (n = 9) of the women who showed symptoms of depression (cut-off 9) at <18 weeks gestation were also depressed at 12 months postpartum. When considering all antenatal timepoints, 5% (n = 12) of women experienced depression both antenatally and at 12 months postpartum. As for postpartum depression, 3% (n = 8) of women experiencing depression at 6 months postpartum also experienced depression at 12 months postpartum.
      Fig. 2
      Fig. 2Prevalence of women with EPDS score indicative for perinatal depression along the study course. <18 weeks of gestation; ±22 weeks; ±36 weeks; 6 weeks postpartum; 6 months postpartum; 12 months postpartum.

      3.3 Maternal red blood cell fatty acid composition and patterns

      Table 2 shows the RBC phospholipid FA composition of the pregnant women at <18 weeks of gestation. Mean RBC phospholipid EPA and DHA was 0.29 ± 0.15% and 5.28 ± 1.15%, respectively. The mean n-3 index (sum of EPA + DHA) was 5.92 ± 1.39%, and 55% and 5% of women had an n-3 index indicative of a low (<6%) and very low (<4%) n-3 PUFA status, respectively. The mean n-6/n-3 PUFA ratio was 4.53 ± 0.94.
      Table 2Red blood cell total phospholipid fatty acid composition of 242 pregnant women at study enrolment (<18 weeks gestation).
      Fatty acid% of total FA
      Mean ±SD.
      SFA
      C14:0Myristic acid0.19 ± 0.10
      C16:0Palmitic acid21.5 ± 2.76
      C18:0Stearic acid16.3 ± 1.62
      C20:0Arachidic acid0.29 ± 0.07
      C22:0Behenic1.43 ± 0.39
      C24:0Lignoceric5.11 ± 1.31
      MUFA
      C16:1n-7Palmitoleic acid0.23 ± 0.09
      C18:1n-7Cis-vaccenic acid0.93 ± 0.15
      C18:1n-7tTrans-vaccenic acid0.07 ± 0.11
      C18:1n-9Oleic acid9.06 ± 1.13
      C18:1n-9tElaidic acid0.11 ± 0.23
      C20:1n-9Gondoic acid0.19 ± 0.04
      C22:1n-9Erucic acid0.00 ± 0.00
      C24:1n-9Nervonic acid4.33 ±1.16
      n-3 PUFA
      C18:3n-3Alpha-linolenic acid (ALA)0.08 ± 0.04
      C18:4n-3Stearidonic acid0.00 ± 0.00
      C20:3n-3Eicosatrienoic acid0.00 ± 0.00
      C20:5n-3Eicosapentaenoic acid (EPA)0.29 ± 0.15
      C22:3n-3Docosatrienoic acid0.01 ± 0.01
      C22:5n-3Docosapentaenoic acid1.85 ± 0.39
      C22:6n-3Docosahexaenoic acid (DHA)5.28 ± 1.15
      n-6 PUFA
      C18:2n-6Linoleic acid11.4 ± 1.70
      C18:3n-6Gamma-linolenic acid0.03 ± 0.02
      C20:2n-6Eicosadienoic acid0.40 ± 0.11
      C20:3n-6Dihomo-gamma-linolenic acid1.25 ± 0.39
      C20:4n-6Arachidonic acid (AA)14.4 ± 1.74
      C22:4n-6Adrenic acid4.32 ± 0.75
      C22:5n-6Osbond acid1.05 ± 0.34
      n-9 PUFA
      C20:3n-9Mead acid0.00 ± 0.00
      a Mean ±SD.
      With the four retained components from PCA, we identified four major RBC FA patterns shown in Table 3: high saturated FA (Pattern 1); low DHA and n-6 PUFA, and high trans FA (Pattern 2); high ALA, EPA, n-3 DPA and n-6 GLA (Pattern 3); and high n-3 PUFA (Pattern 4).
      Table 3Summary of Principal Component Analysis (PCA) factor loadings for four maternal fatty acid patterns after conduction of a PCA on 29 red blood cell phospholipid fatty acids with orthogonal rotation (varimax).
      Phospholipid fatty acidPattern 1
      Pattern 1: High saturated FA
      Pattern 2
      Pattern 2: Low DHA and n-6 PUFA, and high trans FA
      Pattern 3
      Pattern 3: High ALA, EPA, n-3 DPA and n-6 DGLA
      Pattern 4
      Pattern 4: High n-3 PUFA
      SFA
      C14:0Myristic acid0.090.730.34-0.17
      C16:0Palmitic acid-0.260.83-0.08-0.17
      C18:0Stearic acid-0.090.08-0.620.16
      C20:0Arachidic acid0.850.200.060.01
      C22:0Behenic0.890.09-0.010.00
      C24:0Lignoceric0.890.03-0.090.03
      MUFA
      C16:1n-7Palmitoleic acid-0.090.370.38-0.15
      C18:1n-7Cis-vaccenic acid-0.150.020.21-0.09
      C18:1n-7tTrans-vaccenic acid0.220.53-0.150.33
      C18:1n-9Oleic acid-0.400.140.18-0.07
      C18:1n-9tElaidic acid0.140.59-0.200.22
      C20:1n-9Gondoic acid0.630.150.33-0.11
      C22:1n-9Erucic acid0.02-0.37-0.280.42
      C24:1n-9Nervonic acid0.790.00-0.03-0.08
      n-3 PUFA
      C18:3n-3Alpha-linolenic acid (ALA)0.00-0.070.690.17
      C18:4n-3Stearidonic acid-0.17-0.14-0.220.51
      C20:3n-3Eicosatrienoic acid0.100.190.000.58
      C20:5n-3Eicosapentaenoic acid (EPA)-0.04-0.020.460.59
      C22:3n-3Docosatrienoic acid-0.03-0.01-0.040.49
      C22:5n-3Docosapentaenoic acid0.04-0.330.450.41
      C22:6n-3Docosahexaenoic acid (DHA)-0.20-0.470.190.51
      n-6 PUFA
      C18:2n-6Linoleic acid-0.26-0.480.14-0.08
      C18:3n-6Gamma-linolenic acid-0.07-0.040.560.18
      C20:2n-6Eicosadienoic acid0.61-0.250.38-0.11
      C20:3n-6Dihomo-gamma-linolenic acid0.15-0.050.60-0.15
      C20:4n-6Arachidonic acid (AA)-0.45-0.510.060.01
      C22:4n-6Adrenic acid0.20-0.540.01-0.17
      C22:5n-6Osbond acid0.09-0.270.14-0.40
      n-9 PUFA
      C20:3n-9Mead acid0.240.220.180.51
      Eigenvalues4.543.582.852.62
      % of variance33262119
      Factor loadings |0.40| appear in bold. KMO = 0.62 and Bartlett’s test of sphericity X2(406) = 3’653, p <0.001, indicate sufficiently large correlations for PCA.
      a Pattern 1: High saturated FA
      b Pattern 2: Low DHA and n-6 PUFA, and high trans FA
      c Pattern 3: High ALA, EPA, n-3 DPA and n-6 DGLA
      d Pattern 4: High n-3 PUFA

      3.4 Associations of indices of n-3 PUFA status and FA patterns with perinatal depression

      Table 4 shows a summary of results from the conducted multivariate linear regression models on the associations of different FA status indicators at <18 weeks gestation with EPDS scores at 12 months postpartum. In the fully adjusted model 2, RBC EPA at <18 weeks gestation was negatively associated with EPDS scores at 12 months postpartum (β=-0.22; p=0.040). Furthermore, RBC FA pattern 4 (high n-3 PUFA) at <18 weeks gestation was negatively associated with EPDS scores at 12 months postpartum (β=-0.23; p=0.025). We found a positive association of the AA/EPA ratio at <18 weeks gestation with EPDS scores at 12 months postpartum (β=0.24; p=0.022).
      Table 4Multivariate linear regression models assessing associations of different fatty acid status indicators at <18 weeks gestation with Edinburgh Postnatal Depression Scale scores at 12 month postpartum.
      Model 1
      Model 1: “FA status indicator” + age of the mother + gestational age.
      Model 2
      Model 2: ”FA status indicator” + age of the mother + gestational age + BMI at visit 1 + HIV status + LSM score.
      FA StatusΔR2B95% CIβiPΔR2B95% CIβiP
      IndicatorLowerUpperLowerUpper
      DHA (% of total FA)0.10-0.42-1.250.41-0.110.320.17-0.64-1.500.22-0.160.14
      EPA (% of total FA)0.11-5.83-13.11.40-0.160.110.19-7.66-15.0-0.34-0.220.040
      n-3 Index0.10-0.33-1.020.35-0.100.340.17-0.53-1.240.18-0.160.14
      n-6/n-3 ratio0.110.86-0.312.030.150.150.181.15-0.062.360.200.06
      AA/EPA ratio0.120.03-0.010.070.170.090.200.040.010.080.240.022
      Pattern 1 scores
      Pattern 1: High saturated FA.
      0.09-0.30-1.240.64-0.070.530.15-0.27-1.220.68-0.060.57
      Pattern 2 scores
      Pattern 2: Low DHA and n-6 PUFA, and high trans FA.
      0.10-0.61-1.660.44-0.120.250.16-0.61-1.680.45-0.120.26
      Pattern 3 score
      Pattern 3: High ALA, EPA, n-3 DPA and n-6 GLA.
      0.10-0.67-1.890.54-0.110.270.16-0.68-1.890.55-0.120.26
      Pattern 4 score
      Pattern 4: High n-3 PUFA.
      0.12-1.04-2.140.05-0.190.060.20-1.26-2.37-0.16-0.230.025
      a Model 1: “FA status indicator” + age of the mother + gestational age.
      b Model 2: ”FA status indicator” + age of the mother + gestational age + BMI at visit 1 + HIV status + LSM score.
      c Pattern 1: High saturated FA.
      d Pattern 2: Low DHA and n-6 PUFA, and high trans FA.
      e Pattern 3: High ALA, EPA, n-3 DPA and n-6 GLA.
      f Pattern 4: High n-3 PUFA.
      Table 5 displays a summary of results from the conducted logistic regression models on the associations of different FA status indicators at <18 weeks gestation with depression (EPDS score 9) at 12 months postpartum. In the fully adjusted model 2, higher RBC DHA and n-3 index levels at <18 weeks’ gestation were associated with lower odds for depression at 12 months postpartum (OR=0.56 [95% CI: 0.32-0.91]; p=0.030). Likewise, we found that women with higher scores for the RBC FA pattern 3 (high ALA, EPA, n-3 DPA and n-6 GLA) at <18 weeks gestation had lower odds for depression (EPDS 9) at 12 months postpartum (OR=0.47 [95% CI: 0.22-0.92]; p=0.038). On the contrary, higher n-6/n-3 PUFA and AA/EPA ratios at <18 weeks’ gestation were associated with higher odds for depression at 12 months postpartum (OR=2.34 [95% CI: 1.12-4.97]; p=0.016; and OR=1.02 [95% CI: 1.00-1.05]; p=0.023, respectively).
      Table 5Multivariate logistic regression models assessing associations of different fatty acid status indicators at <18 weeks gestation with Edinburgh Postnatal Depression Scale scores with cut-off 9 at12 month postpartum.
      Model 1
      Model 1: “FA status indicator” + age of the mother + gestational age.
      Model 2
      Model 2: ”FA status indicator” + age of the mother + gestational age + BMI at visit 1 + HIV status + LSM score.
      FA statusOdds ratio95% CI ORPOdds ratio95% CI ORP
      IndicatorLowerUpperLowerUpper
      DHA (% of total FA)0.610.370.950.0380.560.320.910.030
      EPA (% of total FA)0.030.001.460.100.010.001.130.09
      n-3 Index0.670.440.970.0450.630.390.940.034
      n-6/n-3 ratio2.191.194.130.0162.341.124.970.016
      AA/EPA ratio1.021.001.040.0501.021.001.050.023
      Pattern 1 score
      Pattern 1: High saturated FA.
      0.780.481.260.320.730.441.220.23
      Pattern 2 score
      Pattern 2: Low DHA and n-6 PUFA, and high trans FA.
      0.860.491.480.600.860.471.550.63
      Pattern 3 score
      Pattern 3: High ALA, EPA, n-3 DPA and n-6 GLA.
      0.500.250.950.0420.470.220.920.038
      Pattern 4 score
      Pattern 4: High n-3 PUFA.
      0.660.351.170.170.660.341.190.19
      a Model 1: “FA status indicator” + age of the mother + gestational age.
      b Model 2: ”FA status indicator” + age of the mother + gestational age + BMI at visit 1 + HIV status + LSM score.
      c Pattern 1: High saturated FA.
      d Pattern 2: Low DHA and n-6 PUFA, and high trans FA.
      e Pattern 3: High ALA, EPA, n-3 DPA and n-6 GLA.
      f Pattern 4: High n-3 PUFA.
      None of the indices of n-3 PUFA status and FA patterns at early pregnancy were associated with depression at the prenatal visits or at 5 weeks and 6 months postpartum (results not shown).

      4. Discussion

      This prospective cohort study conducted in Johannesburg, South Africa, followed 242 pregnant women throughout pregnancy up to 12 months postpartum. We found various associations of different FA status indicators early in pregnancy (<18 weeks of gestation) with perinatal depression at 12 months postpartum. In the multivariate linear regression models, RBC EPA levels were negatively, and the RBC AA/EPA ratio positively associated with EPDS scores at 12 months postpartum. In the multivariate logistic regression models, higher RBC DHA and n-3 index were associated with lower odds for depression, while higher n-6/n-3 PUFA and AA/EPA ratios early in pregnancy were associated with higher odds for depression at 12 months postpartum. We further identified four major RBC FA patterns by conducting a PCA: high saturated FA (Pattern 1); low DHA and n-6 PUFA, and high trans FA (Pattern 2); high ALA, EPA, n-3 DPA and n-6 GLA (Pattern 3); and high n-3 PUFA (Pattern 4). Consistently with the associations observed for the single RBC n-3 PUFA and ratios, higher scores for pattern 4 and pattern 3 were associated with lower EPDS scores and lower odds for depression, respectively. However, we found no significant associations between the various FA status indicators and depression at any of the prenatal or other postnatal time points.
      In our cohort of generally healthy pregnant women, we observed relatively high and constant prevalence rates of depression of around 22% during the pre- and postnatal period (ranging from 17 to 26%). These rates are comparable to the estimated prevalence of perinatal depression in LMIC from recent reviews [
      • Woody C.A.
      • Ferrari A.J.
      • Siskind D.J.
      • Whiteford H.A.
      • Harris M.G.
      A systematic review and meta-regression of the prevalence and incidence of perinatal depression.
      ,
      • Gelaye B.
      • Rondon M.B.
      • Araya R.
      • Williams M.A.
      Epidemiology of maternal depression, risk factors, and child outcomes in low-income and middle-income countries.
      ]. The high prevalence of depression in women from LMIC has been attributed to low socio-economic status, lack of social support, low maternal educational attainment, and sexual abuse [
      • Gelaye B.
      • Rondon M.B.
      • Araya R.
      • Williams M.A.
      Epidemiology of maternal depression, risk factors, and child outcomes in low-income and middle-income countries.
      ,
      • Pellowski J.A.
      • Bengtson A.M.
      • Barnett W.
      • DiClemente K.
      • Koen N.
      • Zar H.J.
      • Stein D.J.
      Perinatal depression among mothers in a South African birth cohort study: Trajectories from pregnancy to 18 months postpartum.
      ]. However, to our knowledge, this is the first study to investigate whether there is a link between maternal n-3 PUFA status and perinatal depression in a LMIC.
      In this study, we observed that women with a higher n-3 PUFA status during early pregnancy have a lower risk for postnatal depression at 12 months postpartum. This is in agreement with a recent prospective cohort study in 72 Belgian women, which reported a low n-3 PUFA status and high n-6/n-3 PUFA ratio during early pregnancy to be associated with an increased risk for postnatal depression at 12 months postpartum [
      • Hoge A.
      • Tabar V.
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      • Castronovo V.
      • Hoge
      • Tabar
      • Donneau
      • Dardenne
      • Degée
      • Timmermans
      • Nisolle
      • Guillaume
      • Castronovo
      Imbalance between omega-6 and omega-3 polyunsaturated fatty acids in early pregnancy is predictive of postpartum depression in a Belgian cohort.
      ]. Nonetheless, literature on protective associations of a higher n-3 PUFA status with a lower risk for perinatal depression remains inconsistent [
      • Lin P.-Y.
      • Chang C.-H.
      • Chong M.F.-F.
      • Chen H.
      • Su K.-P.
      Polyunsaturated fatty acids in perinatal depression: a systematic review and meta-analysis.
      ,
      • Hsu M.C.
      • Tung C.Y.
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      Omega-3 polyunsaturated fatty acid supplementation in prevention and treatment of maternal depression: putative mechanism and recommendation.
      ,
      • Trujillo J.
      • Vieira M.C.
      • Lepsch J.
      • Rebelo F.
      • Poston L.
      • Pasupathy D.
      • Kac G.
      A systematic review of the associations between maternal nutritional biomarkers and depression and/or anxiety during pregnancy and postpartum.
      ]. A recent longitudinal case-control study including 54 Swiss pregnant women with diagnosed anxiety disorder, major depressive disorder, or a mixed anxiety-depression disorder, and 40 healthy controls found lower n-3 PUFA levels and higher n-6/n-3 PUFA ratios to be associated with prenatal and postnatal depression [
      • Urech C.
      • Eussen S.R.
      • Alder J.
      • Stahl B.
      • Boehm G.
      • Bitzer J.
      • Bartke N.
      • Hoesli I.
      Levels of n-3 and n-6 fatty acids in maternal erythrocytes during pregnancy and in human milk and its association with perinatal mental health.
      ]. However, the trends for postnatal depression disappeared when adjusting for prenatal depression [
      • Urech C.
      • Eussen S.R.
      • Alder J.
      • Stahl B.
      • Boehm G.
      • Bitzer J.
      • Bartke N.
      • Hoesli I.
      Levels of n-3 and n-6 fatty acids in maternal erythrocytes during pregnancy and in human milk and its association with perinatal mental health.
      ]. In the current study, the associations between the n-3 PUFA indices and depression at 12 months postpartum remained significant when adjusting for prenatal depression (data not shown). A prospective cohort study (n=2’663) in the South West of England showed no robust association of EPA or DHA with postnatal depression at 8 weeks postpartum [
      • Sallis H.
      • Steer C.
      • Paternoster L.
      • Davey Smith G.
      • Evans J.
      Perinatal depression and omega-3 fatty acids: a mendelian randomisation study.
      ]. In contrast, in a community-based prospective cohort study in Norway (n=43), a low n-3 index in late pregnancy was associated with higher depression scores at 3 months postpartum [
      • Markhus M.W.
      • Skotheim S.
      • Graff I.E.
      • Froyland L.
      • Braarud H.C.
      • Stormark K.M.
      • Malde M.K.
      Low omega-3 index in pregnancy is a possible biological risk factor for postpartum depression.
      ]. Overall, the time point of assessing postpartum depression in these studies differed, ranging from 1 week up to 3 months. Few studies have assessed depression up to 12 months postpartum. Still, symptoms of postnatal depression can occur at any time within the first 21 months postpartum [
      • Rosander M.
      • Berlin A.
      • Forslund Frykedal K.
      • Barimani M.
      Maternal depression symptoms during the first 21 months after giving birth.
      ]. We only found associations of FA status with depression at 12 months postpartum but no other time points. Furthermore, only 3% of women experiencing depression at 6 months postpartum also experienced depression at 12 months postpartum. This finding may indicate a different aetiology of depression at 12 months than at 6 months postpartum.
      There are various mechanisms that may explain the protective role of n-3 PUFA in the aetiology of depression. The most widely researched one is related to EPA and DHA being pre-cursors for the synthesis of anti-inflammatory and inflammation-resolving lipid mediators, while molecules derived from n-6 PUFA mainly exhibit pro-inflammatory properties [
      • Calder P.C.
      • Ahluwalia N.
      • Albers R.
      • Bosco N.
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      • Watzl B.
      • Zhao J.
      A consideration of biomarkers to be used for evaluation of inflammation in human nutritional studies.
      ]. Inflammation is a major risk factor for depression [
      • Lee C.H.
      • Giuliani F.
      The role of inflammation in depression and fatigue.
      ]. Evidence from animal models demonstrates that an imbalance in the n-6/n-3 PUFA ratio in phospholipid membranes in favour of n-6 PUFA can lead to an exaggerated immune response to an inflammatory stimulus, such as stress, and compromise the resolution of inflammation [
      • Liput K.P.
      • Lepczyński A.
      • Ogłuszka M.
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      • Pareek C.S.
      • Czarnik U.
      • Pierzchała M.
      Effects of dietary n-3 and n-6 polyunsaturated fatty acids in inflammation and cancerogenesis.
      ]. Thus, higher n-6/n-3 PUFA and AA/EPA ratios in RBC membranes have been associated with higher levels of inflammation, as well as postpartum depression [
      • Calder P.C.
      N-3 fatty acids, inflammation and immunity: new mechanisms to explain old actions.
      ,
      • Nagayasu Y.
      • Fujita D.
      • Daimon A.
      • Nunode M.
      • Sawada M.
      • Sano T.
      • Ohmichi M.
      Possible prevention of post-partum depression by intake of omega-3 polyunsaturated fatty acids and its relationship with interleukin 6.
      ]. The prevalence of inflammation in our study was high, with 60% of women having elevated C-reactive protein (CRP) or alpha-1 glycoprotein (AGP) concentrations at <18 weeks of gestation (CRP <5 mg/L or AGP <1 g/L). This high prevalence may be related to the high prevalence of overweight and obesity, and infectious disease, such as HIV, in the study population. Thus, our results support the hypothesis of n-3 PUFA and the balance of n-3 to n-6 PUFA playing a role in the aetiology of depression via their immune-modulatory properties [
      • Lee C.H.
      • Giuliani F.
      The role of inflammation in depression and fatigue.
      ,
      • Doney E.
      • Cadoret A.
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      • Lebel M.
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      ].
      In this study, we used various indicators to reflect the n-3 PUFA status of pregnant women. There are limited data on blood levels of PUFA in African women. However, the mean n-3 index in pregnant women participating in the NuPED study is comparable to previously reported n-3 index levels in 101 male and female South African fisher people, where the n-3 index in erythrocyte equivalents was found to be between 4-6% [
      • Stark K.D.
      • Van Elswyk M.E.
      • Higgins M.R.
      • Weatherford C.A.
      • Salem N.
      Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults.
      ,
      • Schloss I.
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      • Tichelaar H.Y.
      • Young G.O.
      • O’Keefe S.J.
      Dietary factors associated with a low risk of colon cancer in coloured West Coast fishermen.
      ]. In contrast to the n-3 index target range for cardiometabolic health of 8-11%, there is no established n-3 index target range for pregnant and lactating women. However, increasing evidence suggests that achieving an n-3 index 8% during pregnancy might reduce the risk of premature birth and is therefore desirable also during pregnancy [
      • von Schacky C.
      Omega-3 fatty acids in pregnancy-the case for a target omega-3 index.
      ].
      In addition to the single n-3 PUFA, the n-3 index and the PUFA ratios, we identified four major RBC FA patterns by conducting a PCA. PCA is used to reduce the data set to a more manageable size while retaining as much of the original information as possible [
      • Field A.
      • Miles J.
      • Field Z.
      Discovering Statistics using R.
      ]. In this study, we used this technique to identify groups of women with similar RBC FA compositions, so called patterns. These patterns, in comparison to single FA status indicators, do consider the interdependencies of FA and therefore can give insight into FA metabolism. The patterns derived in our sample of pregnant women are similar to the FA patterns detected in a sample of Dutch pregnant women from the Generation R Study at early pregnancy [
      • Voortman T.
      • Tielemans M.J.
      • Stroobant W.
      • Schoufour J.D.
      • Kiefte-de Jong J.C.
      • Steenweg-de Graaff J.
      • van den Hooven E.H.
      • Tiemeier H.
      • Jaddoe V.W.
      • Franco O.H.
      Plasma fatty acid patterns during pregnancy and child’s growth, body composition, and cardiometabolic health: the generation R study.
      ], specifically the high saturated FA (Pattern 1) and high n-3 PUFA (Pattern 4) pattern. However, the Dutch study did not determine associations between these patterns and perinatal depression, instead they suggest that FA patterns during pregnancy may affect the offspring’s body composition and cardiometabolic health [
      • Voortman T.
      • Tielemans M.J.
      • Stroobant W.
      • Schoufour J.D.
      • Kiefte-de Jong J.C.
      • Steenweg-de Graaff J.
      • van den Hooven E.H.
      • Tiemeier H.
      • Jaddoe V.W.
      • Franco O.H.
      Plasma fatty acid patterns during pregnancy and child’s growth, body composition, and cardiometabolic health: the generation R study.
      ]. To our knowledge, this is the first study to show that women with higher scores for a RBC FA pattern characterised by high levels of n-3 PUFA at early pregnancy have a lower risk for developing depression at 12 months postpartum.
      A major limitation of this study is the high loss to follow-up during the postnatal period resulting in a relatively small sample size and a potential bias. Participants experiencing a depressive episode might be more prone to drop out of extra-daily activities compared to non-depressed participants. However, the main reason for the high loss to follow-up is that many women in this urban setting moved back to their home towns after giving birth to get support by family members. Furthermore, we did not observe a significant decrease in the prevalence of depression during the course of the study. Therefore, the prevalence of depression observed at the postnatal visits may still be representative of the prevalence in the study population. Strengths of the current study include the prospective design and the long follow-up period until 12 months postpartum, as well as the analysis of n-3 PUFA status by measuring RBC total phospholipid FA composition and expressing it using various indices. Unfortunately, we did not measure RBC total phospholipid FA composition at 6 and 12 months postpartum. However, we assume that the n-3 PUFA status determined during early pregnancy is most representative for habitual dietary intake and is therefore strongly correlated with the n-3 PUFA status during the postpartum period. Major changes in dietary intake during pregnancy and lactation are not expected in this setting due to poor dietary counselling, limited financial means and neglectable seasonal impact on food intake in this urban setting [
      • Asayehu T.T.
      • Lachat C.
      • Henauw S.D.
      • Gebreyesus S.H.
      Dietary behaviour, food and nutrient intake of women do not change during pregnancy in Southern Ethiopia.
      ].

      5. Conclusion

      To conclude, our results indicate that a higher RBC n-3 PUFA status during early pregnancy may lower the risk for perinatal depression at 12 months postpartum. This finding agrees with a previous study in Belgian women showing that a low n-3 PUFA status, alone and combined with a high n-6 status, during early pregnancy is associated with an increased risk for postnatal depression at 12 months postpartum [
      • Hoge A.
      • Tabar V.
      • Donneau A.F.
      • Dardenne N.
      • Degée S.
      • Timmermans M.
      • Nisolle M.
      • Guillaume M.
      • Castronovo V.
      • Hoge
      • Tabar
      • Donneau
      • Dardenne
      • Degée
      • Timmermans
      • Nisolle
      • Guillaume
      • Castronovo
      Imbalance between omega-6 and omega-3 polyunsaturated fatty acids in early pregnancy is predictive of postpartum depression in a Belgian cohort.
      ]. However, evidence on the protective associations of n-3 PUFA status on perinatal depression is inconsistent and the time point of assessing postnatal depression varied from 1 week, a few months up to 12 months postpartum. Therefore, our results suggest a new perspective on postpartum depression, indicating that depression occurring at 12 months postpartum might be particularly sensitive to PUFA status in early pregnancy, which is likely to reflect habitual intake. Potential future studies should explore biochemical mechanisms underlying these associations.

      Funding

      The NuPED study was supported in part by the National Research Foundation of South Africa, Unique Grant 99374 (EAS) (https://www.nrf.ac.za/) and the South African Medical Research Council under a Self-Initiated Research Grant (CMS) (http://www.mrc.ac.za/). The NuPED work has further received financial support from the University of South Africa’s Research Department through the Academic Qualification Improvement Programme (EAS) (www.unisa.ac.za). EO received a PhD fellowship from the Ebnet Foundation, Teufen, Switzerland.

      CRediT authorship contribution statement

      Ester Osuna: Conceptualization, Methodology, Funding acquisition, Writing – original draft, Writing – review & editing. Elizabeth A Symington: Data curation, Methodology, Formal analysis, Funding acquisition, Writing – review & editing. Linda Malan: Data curation, Methodology, Writing – review & editing. Cristian Ricci: Conceptualization, Formal analysis, Writing – review & editing. Lizelle Zandberg: Data curation, Methodology, Writing – review & editing. Cornelius M Smuts: Data curation, Methodology, Funding acquisition, Writing – review & editing. Jeannine Baumgartner: Conceptualization, Data curation, Methodology, Supervision, Formal analysis, Writing – original draft, Writing – review & editing.

      Declaration of Competing Interest

      All authors declare that they have no conflict of interest.

      Acknowledgements

      We thank the following people for their contribution to the NuPED study: Prof A Coovadia, Dr A Wise, Prof H Lombaard, Dr E Loock, Dr R Adams, Dr R Strehlau, Prof M Faber, Dr O Sotunde, Dr M Rothman, Dr L Siziba, Mrs C Cooke, the sonographers and nurses of Rahima Moosa Mother and Child Hospital, the nurses at the primary healthcare clinics, the fieldworkers and the study participants.

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