Table 1 Characteristics of included studies
1st author | Year | Country | Study type | Participants (n) | Time interval | Mean age | Combinable outcomes | RPL definition | Quality |
|---|---|---|---|---|---|---|---|---|---|
Craig [8] | 2002 | USA | Single center, case-controlled, prospective study | RPL (74), Control (74) | April 2000–January 2001 | Case group: 32.7 ± 5.4/Control group: 32.8 ± 6.0/P = 0.92 | FBS, FI, FG/FI, HOMA-IR > 4.5 | 2 or more | Good |
Zolghadri [19] | 2007 | Iran | Prospective control clinical trial | RPL (164), Control (74) | August 2003–June 2005 | Not combinable | 3 or more | Fair | |
Kotanaie [20] | 2012 | Iran | Prospective case–control study | RPL (50), Control (50) | March 2007–March 2008 | Case group: 28.02 ± 4.57/Control group: 28.28 ± 4.77/p = 0/5715 | FBS, FI, FG/FI | 3 or more | Fair |
Diejomaoh [15] | 2007 | Kuwait | Cross-sectional study | RPL (35), Control (30) | October 2002–June 2004 | study group: 28.6 ± 4.3/Control group: 27.5 ± 4.6 | FBS, FI, HOMA-IR, HOMA-IR > 4.5, FG/FI | 3 or more | Fair |
Wang [18] | 2011 | China | Cross-sectional study | RPL (97), Control (52) | June 2008–September 2010 | patient group: 30.81 ± 4.01/control group: 29.15 ± 4.62 | FBS, FI, HOMA-IR > 4.5, | 2 or more | Fair |
Edugbe [16] | 2020 | Nigeria | Multicenter cross-sectional study | RPL (80), Control (80) | NR | Case: 28.09 ± 6.14/Control: 28.10 ± 6.21 | FBS, FI, HOMA-IR, HOMA-IR > 4.5, | 2 ore more | Good |
Habets [17] | 2022 | Netherlands | Retrospective case–control study | Case group: 123 women with either a history of low-order RPL (2–3 pregnancy losses) (65 patients) or high-order RPL (≥ 4 pregnancy losses) (58 patients)/ Control group: 20 healthy women with a history of at least one previous uncomplicated pregnancy | 2015–2019 | Group of RPL = 2 + 3: 32.8[29.5–35.4]/Group of RPL ≥ 4: 33.7[30.4–36.5]/control: 32[29.5–38]/p = 0.390 | FBS, FI | 2 or more | Good |
Ispasoiu [9] | 2013 | Romania | Single center, case–control study | 65 patients in case group and 53 patients in control | 2011–2012 | Case: 30.12 (4.904) Control: 29.36 (5.274) | FBS, FI, HOMA-IR | 2 or more | Fair |
Wani [21] | 2017 | Pakistan | Single center, case-controlled | Case: 75 Non pregnant with history of 2 or more recurrent pregnancy losses Control: 75 non pregnant women with no RPL with at least one live birth | 2014–2015 | Case: 28.4 (2.37) Control: 29.1(2.7) | FBS, FI, HOMA-IR, HOMA-IR > 4.5, FG/FI, FG/FI < 4.5 | 2 or more | Fair |