Summary of included articles
| Authors (year) | Country of origin of cases | Study design | Sample size (cases) (controls) | Matching criteria | Biomarkers analysed | Gestation stage at enrolment |
| Adesanya et al (1991)26 | Benin | Case control | 14 (7) (7) | Age | Albumin; aldosterone; ANP; PRA; sodium (urine) | Postpartum cases and controls |
| Azibani et al (2020)27 | South Africa, Germany | Case control | 247 (151) (96) | Parity | Galectin-3; OPN, PINP; PIIINP; sST2 | Peripartum controls |
| Cénac et al (1990)28 | Nigeria | Case control | 79 (39) (40) | None | Circulating immune complexes; heart muscle autoantibody; IgA; IgG; IgM | Postpartum controls |
| Cénac et al (1992)29 | Niger | Case control* | 71 (35) (36) | None | Selenium | Breastfeeding postpartum controls |
| Cénac et al (1996)30 | Niger | Case control* | 75 (35) (40) | Social class, age | Albumin; copper; pre-albumin; retinol binding protein; selenium; zinc | Breastfeeding postpartum controls |
| Cénac et al (2000)31 | Niger | Case control | 75 (50) (25) | None | Chlamydia (IgA; IgG; IgM)* | Not reported |
| Cénac et al (2004)32 | Mali | Case control | 56 (28) (28) | Parity | Selenium | Not reported |
| Cénac et al (2009)33 | Niger | Case control | 64 (10) (46) | None | Selenium | Postpartum controls |
| Ellis et al (2005)34 | Haiti | Case control | 24 (12) (12) | Age, parity | Anti-HSP60; Anti-HSP70; CRP; endothelin-1; GM-CSF; IFN-g; IL-10; IL-1a; IL-1b; IL-4; proBNP; sCD40L; TGF-b; TNF-a | Postpartum cases and controls |
| Fett et al (2002)35 | Haiti | Case control | 52 (18) (34) | Parity | Beta-carotene; selenium; vitamin A; vitamin B12; vitamin C; vitamin E | Not reported |
| Forster et al (2008)15 | South Africa | Nested case control | 63 (43) (20) | Age, pregnancy | CRP; Fas/Apo-1; IFN-g; IL-1b; IL-6; MMP-2; MMP-9; NT-proBNP; oxLDL; PRL; TGF-b1; TNF-a; VEGF | Postpartum controls |
| Haghikia et al(2013)20 | Germany | Nested case control | 134 (115) (19) | Parity | ADMA; cathepsin-D; miRNA-146a (plasma); NT-proBNP | Peripartum cases. Postpatum controls |
| Haghikia et al (2015)36 | Germany | Case control | 120 (70) (50) | Parity | AAB: MHC and TnI | Postpartum controls |
| Halkein et al (2013)4 | Germany | Case control | 56 (38) (18) | None | ERBB4 mRNA (tissue); miRNA-146a (plasma); miRNA-146a (tissue) | Postpartum controls |
| Hilfiker-Kleiner et al (2007)2 | Germany | Case control | 12 (5) (7) | Age, parity | Cathepsin-D; oxLDL; prolactin (16 kDa); prolactin (26 kDa); STAT3 | Lactating postpartum cases and controls |
| Huang et al (2010)18 | China | Case control | 182 (82) (100) | Occupation, economic status, education, age difference <10 years | ADV-IgG; albumin; AMA-IgG; CBV-IgG; cTnI; hs-CRP; neutrophils; WBC | Postpartum cases and controls |
| Huang et al (2012)37 | China | Nested case control | 104 (52) (52) | Occupation, economic status, education, age difference <10 years | Albumin; cTnI; hs-CRP; NT-proBNP; WBC | Postpartum cases and controls |
| Karaye et al (2015)38 | Nigeria | Case control | 89 (39) (50) | None | Albumin; ceruloplasmin; creatinine; haemoglobin; selenium; sodium (blood) | Postpartum cases and controls |
| Karaye et al (2016)39 | Nigeria | Case control | 131 (54) (77) | None | Creatinine; potassium; sodium (blood) | Postpartum cases and controls |
| Liu et al (2014)40 | China | Case control | 73 (37) (36) | None | AAB: B1R; AAB: M2-R; NT-proBNP | Postpartum cases. Pregnant controls |
| McTiernan et al (2018)41 | USA | Nested case control | 110 (100) (10) | Postpartum days | Macrophages†; monocytes‡; NK cells§; T-cells¶ | Postpartum cases and controls |
| Mebazaa et al (2017)25 | South Africa, France | Case control | 123 (83) (40) | None | Copeptin; MR-proADM; NT-proBNP; PlGF; relaxin-2; sFLT1; sST2; VEGF | Postpartum cases, pregnant controls, controls within 24 hours of delivery |
| Nonhoff et al (2017)42 | Germany | Case control | 112 (55) (57) | Gestation stage | NT-proBNP; relaxin-2 | Peripartum cases. Postpartum controls. Pregnant controls. |
| Patten et al (2012)43 | USA | Case control | 50 (21) (29) | Age, parity | sFLT1 | Postpartum cases. Nursing postpartum controls |
| Ricke-Hoch et al (2019)44 | Germany | Case control | 117 (64) (53) | Age | CRP; IL-1b; IL-6; NT-proBNP; PAI-1; TnT; uPA | Postpartum cases and controls |
| Sagy et al (2017)45 | Israel | Case control | 161 006(42) (160 964) | Gestational age, medical history of cardiac conditions and creatinine) | Albumin; alkaline phosphatase; ALT; ANA; AST; bilirubin; calcium; CPK; creatinine; CRP; D-dimer; GGT; glucose; haemoglobin; phosphorous; platelets; potassium; sodium (blood); TnT; TSH; urea; uric acid; WBC | Peripartum cases and controls. |
| Walenta et al (2012)46 | South Africa, Germany | Case control | 60 (24) (36) | Age, parity | EMP**; LMP; MMP; PMP†† | Pregnant controls. Postpartum controls. |
| Wang et al (2018)47 | China | Nested case control | 22 (11) (11) | None | Albumin; ALT; BNP; CK-MB; creatinine; CRP; haemoglobin; TnI; WBC | Peripartum cases and controls |
| Xia et al (2016)48 | China | Case control | 76 (38) (38) | Parity | ALT; AST; B7-H1 (mRNA); C3; C4; CK-MB; creatinine; fasted blood glucose; haemoglobin; IFN-g; IgA; IgG; IgM; IL-4; PD-1 (mRNA); proBNP; T-cells; TnI | Not reported |
| Xia et al (2017)49 | China | Case control | 76 (38) (38) | Parity | Albumin; ALT; AST; creatinine; B7-H1 (mRNA); B7-H1 (protein); CK-MB; proBNP; fasted blood glucose; haemoglobinA1c; haemoglobin; hs-CRP; IFN-g; IL-4; PD-1 (mRNA); PD-1 (protein); platelets; RBC; TnI; WBC | Not reported |
| Yaqoob et al (2018)50 | India | Case control | 115 (45) (70) | None | ACE polymorphism: DD; ID; II | Peripartum cases. Postpartum controls. |
*Including: Chlamydia pneumonia, Chlamydia trachomatis and Chlamydia psittaci.
†Macrophages included: CD14+CD16+, CD14+ CD16+ CD38+, and CD14+ CD16+ HLA-DR+.
‡Monocytes included: CD14+, CD14+ CD16−, CD14+ CD16 CD38+, and CD14+ CD16−HLA-DR+.
§NK cells included: CD3−CD56+CD16−, CD3−CD56+CD16+, CD3−CD56+CD16+CD38+, and CD3−CD56+CD16+HLA-DR+.
¶T-cells included: CD8+, CD3+, CD4+, CD3+CD4+, CD3+CD4+CD25+, CD3+CD4+CD38+, CD3 +CD4+CD8+, CD3+CD4−CD8−, CD3+CD4 CD8−CD25+, CD3+CD4 CD8−CD38+, CD3+CD4−CD8−HLA-DR+, CD3+CD56+, CD3+CD56+CD8+, CD3+CD8+, CD3+CD8+CD25+, CD3+CD8+CD38+ and CD3+CD8+HLA-DR+.
**EMPs included: CD62E+, CD144+AV+, CD31+AV+ and CD144+CD31+AV+.
††PMPs included: CD42b−AV+, CD62P+and CD62P+CD46b+AV+.
AAB:B1R, auto-antibody: β1-adrenergic receptor; AAB:MHC & TnI, auto-antibody: myosin heavy chain & troponin-1; AAB:M2R, auto-antibody: M2-muscarinic receptor; ADMA, asymmetric dimethylarginine; ADV-IgG, adenovirus immunoglobulin-G; ALT, alanine aminotransferase; AMA-IgG, anti-mitochondrial antibody immunoglobulin-G; ANA, antinuclear antibodies; ANP, Atrial natriuretic peptide; anti-HSP60, anti-Heat shock protein 60; anti-HSP70, anti-Heat shock protein 70; AST, aspartate transaminase; B7-H1, B7 homolog 1; BNP, B-type natriuretic peptide; C3, complement component 3; C4, complement component 4; CBV-IgG, coxsackie b virus immunoglobulin-G; CK-MB, creatine kinase myocardial band; CPK, creatine phosphokinase; CRP, C-reactive protein; cTnI, cardiac troponin-1; DD/ID/II, double-deletion/insertion-deletion/double-insertion; EMP, endothelial microparticles; ErbB4, erb-B2 receptor tyrosine kinase 4; Fas/Apo-1, apoptosis antigen 1; GGT, gamma-glutamyl transpeptidase; GM-CSF, granulocyte-macrophage colony-stimulating factor; hs-CRP, high-sensitivity C-reactive protein; IFN-g, interferon gamma; IgA, immunoglobulin A; IgG, immunoglobulin G; IgM, immunoglobulin M; IL-4, interleukin 4; IL-6, interleukin 6; IL-10, interleukin 10; IL-1a, Interleukin 1 alpha; IL-1b, Interleukin 1 beta; LMP, leukocyte-derived microparticles; MMP-2, matrix metalloproteinase-2; MMP-9, matrix metalloproteinase-9; MMP, monocyte-derived microparticles; MR-proADM, mid regional pro-adrenomedullin; NT-proBNP, N-terminal pro B-type natriuretic peptide; OPN, osteopontin; oxLDL, oxidised low-density lipoprotein; PAI-1, plasminogen activator inhibitor-1; PD-1, programmed cell death protein 1; PIIINP, procollagen type-3 N-terminal propeptide; PINP, procollagen type-1 N-terminal propeptide; PlGF, placental growth factor; PMP, Platelet-derived microparticles; proBNP, pro B-type natriuretic peptide; sCD40L, soluble CD40 ligand; sFTL1, soluble fms-like tyrosine kinase-1; sST2, Soluble suppression of tumorigenicity 2; STAT3, signal transducer and activator of transcription 3; TGF-b, Transforming growth factor beta; TNF-a, tumour necrosis factor alpha; TnT, troponin-T; TSH, thyroid stimulating hormone; uPA, urokinase; VEGF, vascular endothelial growth factor; WBC, white blood cells count.