ABSTRACT

OBJECTIVE

To verify whether folic acid supplementation during pregnancy is associated with the occurrence of maternal depressive symptoms at three months postpartum, in the 2015 Pelotas Birth Cohort.

METHODS

This study included 4,046 women, who were classified into three groups: did not use folic acid supplementation during pregnancy; used during only one trimester of pregnancy; and used for two or three trimesters. Depressive symptoms were assessed at three months postpartum using the Edinburgh Postnatal Depression Scale (EPDS), at cutoff points ≥ 10 (mild symptoms) and ≥ 13 (moderate to severe intensity).

RESULTS

The overall prevalence of mild symptoms was of 20.2% (95%CI 19.0–21.5), and moderate and severe was 11% (95%CI 10.0–12.0). The prevalence of EPDS ≥ 10 was of 26.8% (95%CI 24.0–29.5) among women who did not use folic acid and 18.1% for both those who used it during one trimester of pregnancy (95%CI 16.1–20.1) and those who used it for two or three trimesters (95%CI 16.0–20.2). The prevalence of EPDS ≥ 13 was of 15.7% (95%CI 13.5–17.9) in those who did not use folic acid, 9.1% (95%CI 7.5–10.6) in those who used it for one trimester, and 9.4% (95%CI 7.8–11.0) in those who used it for two or three trimesters. In the adjusted analyses, there was no statistically significant association between the use of folic acid during pregnancy and the occurrence of depressive symptoms at three months postpartum.

CONCLUSION

There was no association between folic acid supplementation during pregnancy and postpartum depression at three months.

Pregnancy; Folic Acid; Depression, Postpartum; Cohort Studies

INTRODUCTION

Depressive disorders are classified by the World Health Organization (WHO) as the largest contributor to global disability, particularly among women ¹1. World Health Organization. Mental health action plan 2013-2020 . Geneva: World Health Organization; 2013. , ²2. World Health Organization. Depression and other common mental disorders: global health estimates. Geneva: World Health Organization; 2017. . They are characterized by sadness, loss of interest or pleasure, feelings of guilt or low self-worth, disturbed sleep or appetite, feelings of tiredness, and poor concentration, which can be long-lasting or recurrent, substantially impairing the individual’s ability to cope with daily life ¹1. World Health Organization. Mental health action plan 2013-2020 . Geneva: World Health Organization; 2013. , ²2. World Health Organization. Depression and other common mental disorders: global health estimates. Geneva: World Health Organization; 2017. .

Postpartum depression (PPD) is a common complication of pregnancy ³3. Yan J, Liu Y, Cao L, Zheng Y, Li W, Huang G. Association between duration of folic acid supplementation during pregnancy and risk of postpartum depression. Nutrients. 2017 Nov;9(11):1206. https://doi.org/10.3390/nu9111206
https://doi.org/10.3390/nu9111206... , in which the severity depends on factors such as socioeconomic context and family support ⁴4. Ministério da Saúde (BR). Secretaria de Atenção à Saúde. Departamento de Atenção B, Brasil. Atenção ao pré-natal de baixo risco. Brasília, DF: Ministério da Saúde; 2012. (Série A, Normas e Manuais Técnicos, Caderno de Atenção básica, v. 32). . PPD has adverse consequences not only for the mother, but also for the family since it can affect child development (for example, it is associated with a higher risk of low birth weight in the first year of life ⁵5. Farías-Antúnez S, Xavier MO, Santos IS. Effect of maternal postpartum depression on offspring’s growth. J Affect Disord. 2018 Mar;228:143-52. https://doi.org/10.1016/j.jad.2017.12.013
https://doi.org/10.1016/j.jad.2017.12.01... ), create difficulties in establishing mother-fetal bonding ⁶6. Dubber S, Reck C, Müller M, Gawlik S. Postpartum bonding: the role of perinatal depression, anxiety and maternal-fetal bonding during pregnancy. Arch Women Ment Health. 2015 Apr;18(2):187-95. https://doi.org/10.1007/s00737-014-0445-4
https://doi.org/10.1007/s00737-014-0445-... , and cause impairment in social, affective, and cognitive development aspects ⁷7. Brummelte S, Galea LA. Postpartum depression: etiology, treatment and consequences for maternal care. Horm Behav. 2016 Jan;77:153-66. https://doi.org/10.1016/j.yhbeh.2015.08.008
https://doi.org/10.1016/j.yhbeh.2015.08.... , ⁸8. Moehler E, Brunner R, Wiebel A, Reck C, Resch F. Maternal depressive symptoms in the postnatal period are associated with long-term impairment of mother-child bonding. Arch Women Ment Health. 2006 Sep;9(5):273-8. https://doi.org/10.1007/s00737-006-0149-5
https://doi.org/10.1007/s00737-006-0149-... .

A systematic review of 16 international studies, including approximately 35,000 women, indicated a mean prevalence of 17% for puerperal women with a high probability of having PPD. Most studies used the Edinburgh Postnatal Depression Scale (EPDS), with cutoff points ranging from 9 to 13 ⁹9. Underwood L, Waldie K, D’Souza S, Peterson ER, Morton S. A review of longitudinal studies on antenatal and postnatal depression. Arch Women’s Ment Health. 2016 Oct;19(5):711-20. https://doi.org/10.1007/s00737-016-0629-1
https://doi.org/10.1007/s00737-016-0629-... . Data from a Brazilian study with approximately 23,000 women from all regions of the country indicated an even higher prevalence, of approximately 25%, using EPDS ≥ 13 ¹⁰10. Theme Filha MM, Ayers S, Gama SG, Leal MC. Factors associated with postpartum depressive symptomatology in Brazil: the birth in Brazil National Research Study, 2011/2012. J Affect Disord. 2016 Apr;194:159-67. https://doi.org/10.1016/j.jad.2016.01.020
https://doi.org/10.1016/j.jad.2016.01.02... .

The etiology of PPD is believed to be linked to biological, genetic, hormonal, psychosocial and environmental factors ³3. Yan J, Liu Y, Cao L, Zheng Y, Li W, Huang G. Association between duration of folic acid supplementation during pregnancy and risk of postpartum depression. Nutrients. 2017 Nov;9(11):1206. https://doi.org/10.3390/nu9111206
https://doi.org/10.3390/nu9111206... . Deficiency of nutritional factors such as folate/folic acid, vitamin B12, polyunsaturated fatty acids, selenium, zinc, calcium, and iron has also been associated with PPD ³3. Yan J, Liu Y, Cao L, Zheng Y, Li W, Huang G. Association between duration of folic acid supplementation during pregnancy and risk of postpartum depression. Nutrients. 2017 Nov;9(11):1206. https://doi.org/10.3390/nu9111206
https://doi.org/10.3390/nu9111206... , ¹¹11. Baskin R, Hill B, Jacka FN, O’Neil A, Skouteris H. The association between diet quality and mental health during the perinatal period: a systematic review. Appetite. 2015 Aug;91:41-7. https://doi.org/10.1016/j.appet.2015.03.017
https://doi.org/10.1016/j.appet.2015.03.... . Folic acid is part of the vitamin B complex (vitamin B9). A meta-analysis of observational studies showed that low folate levels are associated with depression in the general population ¹⁴14. Bender A, Hagan KE, Kingston N. The association of folate and depression: a meta-analysis. J Psychiatr Res. 2017 Dec;95:9-18. https://doi.org/10.1016/j.jpsychires.2017.07.019
https://doi.org/10.1016/j.jpsychires.201... . Folate is a major determinant of 1-carbon metabolism, where S-Adenosylmethionine (SAM) is formed. SAM donates important methyl groups for neurological function. Furthermore, increased plasma homocysteine is a functional marker of folate deficiency, and elevated homocysteine levels are found in depressive patients ¹⁵15. Behzadi AH, Behbahani AS, Ostovar N. Therapeutic effects of folic acid on ante partum and postpartum depression. Med Hypotheses. 2008 Aug;71(2):313-4. https://doi.org/10.1016/j.mehy.2008.03.029
https://doi.org/10.1016/j.mehy.2008.03.0... , ¹⁶16. Gilbody S, Lightfoot T, Sheldon T. Is low folate a risk factor for depression? A meta-analysis and exploration of heterogeneity. J Epidemiol Community Health. 2007 Jul;61(7):631-7. https://doi.org/10.1136/jech.2006.050385
https://doi.org/10.1136/jech.2006.050385... .

WHO recommends daily oral supplementation of iron and folic acid as part of prenatal care to reduce the risk of low birth weight, maternal anemia, and iron deficiency ¹⁷17. Organização Mundial da Saúde. Diretriz: suplementação diária de ferro e ácido fólico em gestantes. Genebra: Organização Mundial da Saúde; 2013. . In Brazil, folic acid supplementation is indicated at least 30 days before conception until the end of pregnancy, at a dose of 0.4mg per day, to prevent neural tube defects and anemia ¹⁸18. Ministério da Saúde (BR). Protocolos da atenção básica: saúde das mulheres. Brasília, DF: Ministério da Saúde; 2016. . There are few published studies that evaluated the association between folic acid supplementation or folate levels during pregnancy and the occurrence of PPD ³3. Yan J, Liu Y, Cao L, Zheng Y, Li W, Huang G. Association between duration of folic acid supplementation during pregnancy and risk of postpartum depression. Nutrients. 2017 Nov;9(11):1206. https://doi.org/10.3390/nu9111206
https://doi.org/10.3390/nu9111206... , ¹⁹19. Chong MF, Wong JX, Colega M, Chen LW, Dam RM, Tan CS, et al. Relationships of maternal folate and vitamin B12 status during pregnancy with perinatal depression: the GUSTO study. J Psychiatr Res. 2014 Aug;55:110-6. https://doi.org/10.1016/j.jpsychires.2014.04.006
https://doi.org/10.1016/j.jpsychires.201... , only two of which were population-based ²⁰20. Lewis SJ, Araya R, Leary S, Smith GD, Ness A. Folic acid supplementation during pregnancy may protect against depression 21 months after pregnancy, an effect modified by MTHFR C677T genotype. Eur J Clin Nutr. 2012 Jan;66(1):97-103. https://doi.org/10.1038/ejcn.2011.136
https://doi.org/10.1038/ejcn.2011.136... , ²¹21. Blunden CH, Inskip HM, Robinson SM, Cooper C, Godfrey KM, Kendrick TR. Postpartum depressive symptoms: the B-vitamin link. Ment Health Fam Med. 2012 Jan;9(1):5-13. . Thus, the objective of this study is to evaluate the prevalence of depressive symptoms at three months after childbirth and its relationship with the use of folic acid supplementation among mothers belonging to the 2015 Pelotas Birth Cohort ( Coorte de Nascimentos de Pelotas de 2015 – C2015).

METHODS

The data from this study are part of C2015, held in the city of Pelotas, in the state of Rio Grande do Sul, in southern Brazil. All women who gave birth in the five maternity hospitals in Pelotas, from January 1, 2015, to December 31, 2015, and who lived in the urban area of the municipality and in Colônia Z3, as well as in the Jardim América neighborhood, adjacent to Pelotas and belonging to the municipality of Capão do Leão, were invited to participate in the study. Methodological details can be found elsewhere ²³23. Hallal PC, Bertoldi AD, Domingues MR, Silveira MF, Demarco FF, Silva ICM, et al. Cohort profile: the 2015 Pelotas (Brazil) birth cohort study. Int J Epidemiol. 2018;47(4):1048-1048-h. https://doi.org/10.1093/ije/dyx219
https://doi.org/10.1093/ije/dyx219... .

This cohort started in 2014, in the prenatal period. The 123 health units and private clinics that offer prenatal care in the city were visited weekly, between May 2014 and December 2015, to identify pregnant women with a probable date of delivery for the year 2015. These women were visited at home or invited to attend the research clinic, between 16 and 24 weeks of gestation, to answer a health questionnaire, including questions about the use of medications and vitamins ²³23. Hallal PC, Bertoldi AD, Domingues MR, Silveira MF, Demarco FF, Silva ICM, et al. Cohort profile: the 2015 Pelotas (Brazil) birth cohort study. Int J Epidemiol. 2018;47(4):1048-1048-h. https://doi.org/10.1093/ije/dyx219
https://doi.org/10.1093/ije/dyx219... .

In the perinatal study, mothers were interviewed after delivery, during their stay in the maternity ward, answering a standardized questionnaire about the prenatal period, including the use of medications and vitamins. Given that 75% of the puerperal women had also been interviewed during the C2015 prenatal study, it was possible to complement the information on the use of medications and vitamins captured in the perinatal study with data obtained at a time closer to their use. This strategy allowed qualifying the information, bearing in mind that, during the prenatal period, the recall period was shorter, and, as the interviews were carried out at home, it was possible to verify the prescriptions and packaging of the products used.

In both the prenatal and perinatal studies, information regarding the use of folic acid was obtained through the following questions: “Have you used or are you using any vitamins, calcium, folic acid or iron salts since you became pregnant?” If so, the names of these drugs were questioned and, later, for each drug reported, the following questions were asked, with the aim of characterizing its use: “In which trimester of pregnancy did you use this drug?” 1st trimester (up to week 13), 2nd trimester (week 14 to 27), and 3rd trimester (week 28 onwards or still in use). For the current study, we considered the use of folic acid alone or in association with other vitamins and/or mineral salts, regardless of dosage.

The three-month postpartum follow-up was performed at the research clinic. On that occasion, maternal depressive symptoms were assessed using the EPDS. This scale consists of 10 items, each with a score ranging from zero to three. The EPDS was validated for use in Brazil, with the cutoff point ≥ 10 being considered the best to identify mothers with mild depressive symptoms in the postpartum period, with a sensitivity of 82.7% (75.3–89.9) and specificity of 65.4% (59.8–71.1) ²⁴24. Santos IS, Matijasevich A, Tavares BF, Barros AJ, Botelho IP, Lapolli C, et al. Validation of the Edinburgh Postnatal Depression Scale (EPDS) in a sample of mothers from the 2004 Pelotas Birth Cohort Study. Cad Saude Publica. 2007 Nov;23(11):2577-88. https://doi.org/10.1590/S0102-311X2007001100005
https://doi.org/10.1590/S0102-311X200700... ; and the cutoff ≥ 13 for depressive symptoms of moderate to severe intensity, with sensitivity of 59.6% (49.5–69.1) and specificity of 88.3% (83.9–91.9) ²⁴24. Santos IS, Matijasevich A, Tavares BF, Barros AJ, Botelho IP, Lapolli C, et al. Validation of the Edinburgh Postnatal Depression Scale (EPDS) in a sample of mothers from the 2004 Pelotas Birth Cohort Study. Cad Saude Publica. 2007 Nov;23(11):2577-88. https://doi.org/10.1590/S0102-311X2007001100005
https://doi.org/10.1590/S0102-311X200700... . For this study, mothers who attended the three-month follow-up but did not respond to the EPDS were excluded.

The potential confounders analyzed were: age (< 20, 20–34, and ≥ 35 years); color (white, black, and mixed/other); education (0–4, 5–8, 9–11, and ≥ 12 years of schooling); income in minimum wages (MW), considering the value of R$788.00 in force during the year 2015 ( ≤ 1, 1.1–3, 3.1–6 , 6.1–10, and > 10); parity (1, 2, 3, and ≥ 4 children); living with a partner (yes/no); support from the baby’s father during pregnancy (a lot, more or less/a little, no support); depressive symptoms during pregnancy (EPDS ≥ 11) ²⁵25. Couto TC, Brancaglion MYM, Cardoso MN, Bergo Protzner A, Duarte Garcia F, Nicolato R, et al. What is the best tool for screening antenatal depression? J Affect Disord. 2015 Jun;178:12-7. https://doi.org/10.1016/j.jad.2015.02.003
https://doi.org/10.1016/j.jad.2015.02.00... , reported in the prenatal study; trimester of prenatal care initiation (1st, 2nd, or 3rd); number of prenatal consultations (< 6 or ≥ 6); smoking during pregnancy (yes/no); drinking during pregnancy (yes/no); and physical activity during pregnancy (150 minutes or more per week in at least one trimester) (yes/no). Age was collected in complete years and subsequently categorized. Skin color was self-reported by the mothers. Education was collected in complete years of schooling and subsequently categorized. Family income was reported in reais and later categorized into MW. For parity, the current pregnancy was also considered, without including stillbirths, and categorized later. For a complementary analysis, the use of antidepressant drugs from birth to three months postpartum (yes/no) was considered.

Data analysis was performed using the Stata ^® statistical program, version 12.1. The sample was described showing the proportions of independent variables and 95% confidence intervals (95%CI). Women were classified into three groups regarding exposure to folic acid: did not use of folic acid during pregnancy, used during only one trimester of pregnancy, and used folic acid during two or three trimesters. The mean and standard deviation (SD) of the continuous EPDS score and the prevalence of the EPDS ≥ 10 and EPDS ≥ 13 outcomes, with 95%CI, were calculated for each category of folic acid use.

Adjusted analyses were performed using Poisson regression for the two outcomes: EPDS ≥ 10 and EPDS ≥ 13. Variables were selected in backward mode, with p-values < 0.20 maintained in the model. The significance level adopted to consider statistically significant associations was 0.05. The variables age, education (years of schooling), income, number of prenatal consultations and parity were analyzed continuously. All variables included in the model were tested for their association with the use of folic acid and postpartum depressive symptoms, showing statistically significant relationships.

Additionally, two complementary analyses were performed: A) by multinomial logistic regression, with the outcome in three categories: EPDS < 10, EPDS 10 to 12, and EPDS ≥ 13; and B) by linear regression, with the EPDS outcome in continuous form. An interaction test was also performed between the use of folic acid and depressive symptoms during pregnancy (EPDS ≥ 11).

The study was approved by the Ethics Committee of the Escola Superior de Educação Física, Universidade Federal de Pelotas , under Protocol 522,064, registered on Plataforma Brasil. All interviews were carried out after signing the informed consent form by the mothers.

RESULTS

The 2015 Pelotas Birth Cohort is composed of live births of 4,220 women. There were 160 losses at the three-month follow-up, and 14 women did not answer the EPDS. The EPDS score at three months postpartum ranged from 0 to 27, with a mean of 5.99 points (SD = 4.83). The prevalence of mild depressive symptoms (EPDS ≥ 10) was 20.2% (95%CI: 19.0–21.5), and of moderate and severe symptoms (EPDS ≥ 13), 11.0% (95%CI: 10.0–12.0).

Table 1 presents the characteristics of the analyzed sample, according to the independent variables and the comparison with the original cohort (initial sample collected in the perinatal study). Most mothers reported being white (70.8%), aged between 20 and 34 years (70.8%), living with a partner (85.8%), having received a lot of support from the baby’s father during pregnancy (89 %), having started prenatal care in the first trimester of pregnancy (55.5%), and having had six or more consultations (86.6%). Just over a third (34.5%) had 9 to 11 years of schooling, about half (47.2%) had a family income of 1.1 to 3 MW, and 50.0% were primiparous. Regarding health behaviors, 7.4% reported having consumed alcohol during the gestational period, 16.1% were smokers, and only 10.1% practiced physical activity during this period. Among the women who had been enrolled in the prenatal study (n = 3,029), 24% had an EPDS ≥ 11. There were no statistically significant differences between the original cohort and the analyzed cohort regarding the independent variables ( Table 1 ).

Among the 4,046 women included in the current analysis, 3,987 reported information about folic acid use. Among these, 2,966 (74.4%; 95%CI: 73.0–75.7) reported having used folic acid during pregnancy. Among those who used it, 88.4% (n = 2,621) used an exclusive folic acid supplement (without any other vitamins or mineral salts) at some point during pregnancy. The Figure shows the trimesters of folic acid use by women participating in the study. Of the 2,966 women who reported having used folic acid during pregnancy, only 2,689 informed the trimester of use. Among these, 43.8% used folic acid only during the first trimester.

Table 2 shows the mean and SD of EPDS at three months and the prevalence of outcomes EPDS ≥ 10 and ≥ 13 according to exposure categories. Among women who did not use folic acid during pregnancy, the mean EPDS score was 6.8 (SD = 5.3); among those who used it during one trimester, 5.7 (SD = 4.7); and among those who used it for two or three trimesters, 5.7 (SD = 4.6).

Among women who did not use folic acid, the prevalence of EPDS ≥ 10 was 26.8% (95%CI: 24.0–29.5), and 18.1% both among those who used it during one trimester of pregnancy (95%CI: 16.1–20.1) and among those who used it for two or three trimesters (95%CI: 16.0–20.2) ( Table 2 ). The prevalence of EPDS ≥ 13 was 15.7% (95%CI: 13.5–17.9) among women who did not use folic acid, 9.1% (95%CI: 7.5–10.6) among those who used it for one trimester and 9.4% (95%CI: 7.8–11.0) among those who used it for two or three trimesters ( Table 2 ).

Table 3 shows the prevalence ratios for EPDS ≥ 10 and EPDS ≥ 13, with the respective 95%CI, obtained in the raw analysis and in the adjusted models. For mild depressive symptoms (EPDS ≥ 10), the variables that remained for adjustment in the final model were schooling, support from the baby’s father, drinking during pregnancy, parity, and depressive symptoms during pregnancy. As for moderate and severe symptoms (EPDS ≥ 13), the variables that remained in the final model were “living with a partner”, “parity,” and “depressive symptoms during pregnancy”.

In the raw analysis, the use of folic acid was significantly associated with a decrease in the risk of postpartum depressive symptoms at three months, both among users of folic acid for only one trimester and among those who used it for two trimesters or more, in both EPDS cutoff points ( Table 3 ). In the adjusted analyses, however, there was no statistically significant association between use of folic acid during pregnancy and occurrence of depressive symptoms at three months postpartum, considering the two cutoff points.

In the complementary analyses, both in the multinomial logistic regression and in the linear regression, the results were similar and in the same direction of the Poisson regression analyses. The interaction test did not indicate that the variable “depressive symptoms during pregnancy” modified the association between folic acid use and depressive symptoms in the postpartum period. Additionally, control was also performed for antidepressant use, with no changes in the results. Only 23 women (0.5% of the sample) were using antidepressants from birth to three months postpartum. Seven of them scored above 10 on the Edinburgh questionnaire, four of them with moderate to severe symptoms.

DISCUSSION

The prevalence of mild depressive symptoms at three months postpartum was 20.2% and of moderate to severe depressive symptoms, 11%. The use of folic acid during pregnancy had a protective effect in the raw analysis for both cutoff points, but lost significance in the adjusted analyses.

Several studies have reported the relationship between folate and depression in the general population ¹⁴14. Bender A, Hagan KE, Kingston N. The association of folate and depression: a meta-analysis. J Psychiatr Res. 2017 Dec;95:9-18. https://doi.org/10.1016/j.jpsychires.2017.07.019
https://doi.org/10.1016/j.jpsychires.201... , ¹⁶16. Gilbody S, Lightfoot T, Sheldon T. Is low folate a risk factor for depression? A meta-analysis and exploration of heterogeneity. J Epidemiol Community Health. 2007 Jul;61(7):631-7. https://doi.org/10.1136/jech.2006.050385
https://doi.org/10.1136/jech.2006.050385... , ²⁶26. Beydoun MA, Shroff MR, Beydoun HA, Zonderman AB. Serum folate, vitamin B-12, and homocysteine and their association with depressive symptoms among U.S. adults. Psychosom Med. 2010 Nov;72(9):862-73. https://doi.org/10.1097/PSY.0b013e3181f61863
https://doi.org/10.1097/PSY.0b013e3181f6... , ²⁷27. Huang Q, Liu H, Suzuki K, Ma S, Liu C. Linking what we eat to our mood: a review of diet, dietary antioxidants, and depression. Antioxidants. 2019 Sep;8(9):376. https://doi.org/10.3390/antiox8090376
https://doi.org/10.3390/antiox8090376... , but there is not much evidence in relation to PPD. One study observed low folate and vitamin B12 serum levels and high homocysteine levels in women of childbearing age with psychotic disorders ²⁸28. McColl H, Dhillon M, Howard LM. A systematic review of the nutritional status of women of a childbearing age with severe mental illness. Arch Women Ment Health. 2013 Feb;16(1):39-46. https://doi.org/10.1007/s00737-012-0315-x
https://doi.org/10.1007/s00737-012-0315-... . Folic acid supplements have already been studied as an adjuvant treatment for depression ¹⁵15. Behzadi AH, Behbahani AS, Ostovar N. Therapeutic effects of folic acid on ante partum and postpartum depression. Med Hypotheses. 2008 Aug;71(2):313-4. https://doi.org/10.1016/j.mehy.2008.03.029
https://doi.org/10.1016/j.mehy.2008.03.0... , ²⁹29. Papakostas GI, Shelton RC, Zajecka JM, Etemad B, Rickels K, Clain A, et al. L-methylfolate as adjunctive therapy for SSRI-resistant major depression: results of two randomized, double-blind, parallel-sequential trials. Am J Psychiatry. 2012 Dec;169(12):1267-74. https://doi.org/10.1176/appi.ajp.2012.11071114
https://doi.org/10.1176/appi.ajp.2012.11... , and folic acid rich diets have suggested a reduced risk of depression in some populations ³⁰30. Murakami K, Mizoue T, Sasaki S, Ohta M, Sato M, Matsushita Y, et al. Dietary intake of folate, other B vitamins, and ω-3 polyunsaturated fatty acids in relation to depressive symptoms in Japanese adults. Nutrition. 2008 Feb;24(2):140-7. https://doi.org/10.1016/j.nut.2007.10.013
https://doi.org/10.1016/j.nut.2007.10.01... , ³¹31. Tolmunen T, Voutilainen S, Hintikka J, Rissanen T, Tanskanen A, Viinamäki H, et al. Dietary folate and depressive symptoms are associated in middle-aged Finnish men. J Nutr. 2003 Oct;133(10):3233-6. https://doi.org/10.1093/jn/133.10.3233
https://doi.org/10.1093/jn/133.10.3233... . The study by Yan ³3. Yan J, Liu Y, Cao L, Zheng Y, Li W, Huang G. Association between duration of folic acid supplementation during pregnancy and risk of postpartum depression. Nutrients. 2017 Nov;9(11):1206. https://doi.org/10.3390/nu9111206
https://doi.org/10.3390/nu9111206... found a lower risk for PPD in pregnant women who had taken folic acid supplementation for more than six months, compared with those who supplemented for less than six months. Possible hypotheses for this difference and limitations of that study would be the exclusion of women who did not use folic acid or who used it only in the preconception period, and the non-inclusion of depression symptoms during the gestational period as a confounding factor. The study was carried out with women who underwent postpartum review at maternal and child health centers in Tianjin, China, and used a scale designed for screening depressive symptoms in the general population ³3. Yan J, Liu Y, Cao L, Zheng Y, Li W, Huang G. Association between duration of folic acid supplementation during pregnancy and risk of postpartum depression. Nutrients. 2017 Nov;9(11):1206. https://doi.org/10.3390/nu9111206
https://doi.org/10.3390/nu9111206... .

Other studies found no relationship between folic acid supplementation/folate levels and postpartum depression. Blunden et al. ²¹21. Blunden CH, Inskip HM, Robinson SM, Cooper C, Godfrey KM, Kendrick TR. Postpartum depressive symptoms: the B-vitamin link. Ment Health Fam Med. 2012 Jan;9(1):5-13. found no significant differences between women with or without postpartum depressive symptoms in terms of folate concentration in red blood cells or dietary intake of folate, vitamin B12 and vitamin B6, before or during pregnancy. Chong et al. ¹⁹19. Chong MF, Wong JX, Colega M, Chen LW, Dam RM, Tan CS, et al. Relationships of maternal folate and vitamin B12 status during pregnancy with perinatal depression: the GUSTO study. J Psychiatr Res. 2014 Aug;55:110-6. https://doi.org/10.1016/j.jpsychires.2014.04.006
https://doi.org/10.1016/j.jpsychires.201... also did not observe differences in plasma folate concentrations in women with and without PPD, but folate concentrations were significantly lower among those with probable gestational depression than among those without symptoms. Miyake et al. ²²22. Miyake Y, Sasaki S, Tanaka K, Yokoyama T, Ohya Y, Fukushima W, et al.; Osaka Maternal and Child Health Study Group. Dietary folate and vitamins B12, B6, and B2 intake and the risk of postpartum depression in Japan: the Osaka Maternal and Child Health Study. J Affect Disord. 2006 Nov;96(1-2):133-8. https://doi.org/10.1016/j.jad.2006.05.024
https://doi.org/10.1016/j.jad.2006.05.02... found no association between intake of folate, cobalamin or pyridoxine and the risk of PPD. In the study by Lewis et al. ²⁰20. Lewis SJ, Araya R, Leary S, Smith GD, Ness A. Folic acid supplementation during pregnancy may protect against depression 21 months after pregnancy, an effect modified by MTHFR C677T genotype. Eur J Clin Nutr. 2012 Jan;66(1):97-103. https://doi.org/10.1038/ejcn.2011.136
https://doi.org/10.1038/ejcn.2011.136... found no evidence that folic acid supplementation would reduce the risk of depression during pregnancy and up to eight months postpartum. However, the same study showed that folic acid supplements during pregnancy protected against depression 21 months postpartum, and that this effect was more pronounced in women with the MTHFR C677T TT genotype.

The plausibility for the potential protective effect of folate on the occurrence of PPD stems from the fact that this and other nutrients are important in the neurotransmission system, and pregnancy tends to lead to its depletion ¹²12. Leung BM, Kaplan BJ. Perinatal depression: prevalence, risks, and the nutrition link: a review of the literature. J Am Diet Assoc. 2009 Sep;109(9):1566-75. https://doi.org/10.1016/j.jada.2009.06.368
https://doi.org/10.1016/j.jada.2009.06.3... , ¹³13. Sparling TM, Henschke N, Nesbitt RC, Gabrysch S. The role of diet and nutritional supplementation in perinatal depression: a systematic review. Matern Child Nutr. 2017 Jan;13(1):mcn.12235. https://doi.org/10.1111/mcn.12235
https://doi.org/10.1111/mcn.12235... , ³²32. Rechenberg K, Humphries D. Nutritional interventions in depression and perinatal depression. Yale J Biol Med. 2013 Jun;86(2):127-37. . Folate concentrations in maternal serum and erythrocytes decrease from the fifth month of pregnancy and tend to remain low for a long period after delivery ³³33. Smits LJ, Essed GG. Short interpregnancy intervals and unfavourable pregnancy outcome: role of folate depletion. Lancet. 2001 Dec;358(9298):2074-7. https://doi.org/10.1016/S0140-6736 (01)07105-7
https://doi.org/10.1016/S0140-6736 (01)0... . Folate, vitamin B12, and vitamin B6 are critical factors in the metabolism of homocysteine, which is a necessary precursor in the biosynthesis of the neurotransmitters serotonin, dopamine, and norepinephrine, which are implicated in the pathogenesis of depression ²⁷27. Huang Q, Liu H, Suzuki K, Ma S, Liu C. Linking what we eat to our mood: a review of diet, dietary antioxidants, and depression. Antioxidants. 2019 Sep;8(9):376. https://doi.org/10.3390/antiox8090376
https://doi.org/10.3390/antiox8090376... , ³²32. Rechenberg K, Humphries D. Nutritional interventions in depression and perinatal depression. Yale J Biol Med. 2013 Jun;86(2):127-37. .

Two randomized trials, published in the early 1990s, demonstrated that folic acid supplementation prevented the occurrence and recurrence of neural tube defects ³⁴34. Czeizel AE, Dudás I. Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. N Engl J Med. 1992 Dec;327(26):1832-5. https://doi.org/10.1056/NEJM199212243272602
https://doi.org/10.1056/NEJM199212243272... , ³⁵35. MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991 Jul;338(8760):131-7. https://doi.org/10.1016/0140-6736 (91)90133-A
https://doi.org/10.1016/0140-6736 (91)90... , thus recommending universal supplementation in the preconception period and during pregnancy to prevent these defects, as well as to prevent anemia ¹⁷17. Organização Mundial da Saúde. Diretriz: suplementação diária de ferro e ácido fólico em gestantes. Genebra: Organização Mundial da Saúde; 2013. , ¹⁸18. Ministério da Saúde (BR). Protocolos da atenção básica: saúde das mulheres. Brasília, DF: Ministério da Saúde; 2016. . During the study period, the current protocol in Brazil recommended the use of folic acid during the preconception period and only in the first gestational trimester ⁴4. Ministério da Saúde (BR). Secretaria de Atenção à Saúde. Departamento de Atenção B, Brasil. Atenção ao pré-natal de baixo risco. Brasília, DF: Ministério da Saúde; 2012. (Série A, Normas e Manuais Técnicos, Caderno de Atenção básica, v. 32). . However, it is common not to have this supplement prescribed when the woman begins prenatal care late ³⁶36. Miranda VI, Dal Pizzol TS, Silveira MP, Mengue SS, Silveira MF, Lutz BH, et al. The use of folic acid, iron salts and other vitamins by pregnant women in the 2015 Pelotas birth cohort: is there socioeconomic inequality? BMC Public Health. 2019 Jul;19(1):889. https://doi.org/10.1186/s12889-019-7269-0
https://doi.org/10.1186/s12889-019-7269-... .

This study has some limitations. It was not possible to evaluate the dosage of the supplements used, only the information on use by gestational trimester was analyzed, but without the guarantee that the supplement was used during the entire period of the trimester in question. In addition, our analysis is based on self-report, with no dietary recall, consumption of folic acid fortified foods or serum folate levels. Likewise, it was not possible to evaluate the use of supplementation in the preconception period.

Among the strengths of this study is the fact that it is a population-based cohort, with a large sample size, in which, for most participants, the assessment of the medications used was performed at more than one moment (prenatal and perinatal period). To date, this is one of the few studies on this topic carried out in a middle-income country. Several adjustments were also made for known risk factors for PPD.

Our study demonstrated that the apparently existing protective effect between the use of folic acid and DPP disappears after controlling for confounding factors, and several forms of analysis led to the same result. Given that PPD is considered a problem with multifactorial etiology ³⁷37. Ghaedrahmati M, Kazemi A, Kheirabadi G, Ebrahimi A, Bahrami M. Postpartum depression risk factors: a narrative review. J Educ Health Prompt. 2017 Aug;6:60. , ³⁸38. Hutchens BF, Kearney J. Risk factors for postpartum depression: an umbrella review. J Midwifery Womens Health. 2020 Jan;65(1):96-108. https://doi.org/10.1111/jmwh.13067
https://doi.org/10.1111/jmwh.13067... , with negative effects on the woman, the family, and the child, it is important that future studies seek to measure the nutritional status of folate through objective methods, such as serum level measurement.

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