Table 1:

Data Extraction table

Author Date	Gestational age range	Maternal BMI accounted for?	Stated GDM diagnostic criteria	Delivery mode accounted for?	GDMA1 vs A2 accounted for?	Subcategory (a-f)
Abou-Elghait et al. 2012 [14]	3rd, >37 weeks	no	WHO	no	no	histoarchitecture villous maturation fibrin deposition
Akarsu et al. 2017 [15]	3rd, at delivery	no	50g OGTT screen, 100g OGTT diagnostic	operative	A1 only	villous maturation
Arshad et al. 2015 [16]	at delivery	no	WHO	no	yes	Histoarchitecture, villous maturation, fibrin deposition
Ashfaq et al. 2005 [17]	3rd, “term”	no	not specified	no	no	placental size
Basnet et al. 2016 [18]	3rd	no	not specified	no	no	vascular function
Baumüller et al. 2015 [19]	3rd, at delivery	yes	not specified	no	yes	vascular function
Berceanu et al. 2018 [20]	2nd, 3rd, at delivery	no	not specified	no	no	placental size, histoarchitecture
Bhattacharjee et al. 2017 [21]	3rd, >37 weeks	no	Carpenter and Coustan	no	no	villous maturation, villous edema, fibrin deposition
Brown et al. 1990 [22]	3rd, 26–40 weeks	no	not specified	no	no	vascular function
Calderon et al. 2007 [23]	3rd, >34 weeks	no	ADA	no	no	villous maturation, vascular function
Chan et al. 2003 [24]	3rd, delivery	yes	WHO	no	no	placental size
Cosson et al. 2016 [25]	at delivery	yes	75-g OGTT with fasting plasma glucose ≥ 5.3 mmol/L and/or a 2-h ≥ 7.8 mmol/L	no	no	placental size
Cvitic et al. 2018 [26]	3rd, at delivery	no	WHO	no	no	vascular function
Deveci et al. 2013 [27]	3rd, 28–35 weeks	no	not specified	no	no	cellular/subcellular
Dieber-Rotheneder et al. 2012 [28]	3rd, 28–41wks	yes	75 g OGTT: > 95 1h, > 180 1h, >155 mg/dl 2h	no	no	vascular function
Dollberg et al. 1997 [29]	3rd, “term”	no	Carpenter and Coustan	no	no	vascular function
Dubova et al. 2011 [30]	3rd, >37 weeks	no	not specified	no	A1 only	villous maturation
Edu et al. 2016 [31]	2nd, 3rd	no	IADPSG	no	no	placental size, villous maturation, villous edema, fibrin deposition
Erkamp et al. 2020 [32]	1st, 2nd, 3rd	yes (lean)	Dutch guidelines: random glucose >11.0 mmol/l, fasting ≥7.0 mmol/l, or fasting 6.1–6.9 mmol/l with abnormal GTT	no	no	vascular function
Fadda et al. 2001 [33]	2nd, 3rd	no	National Diabetes Data Group (1979)	yes	yes	vascular function
Feng et al. 2016 [34]	3rd, “term”	no	75 g OGTT	no	no	cellular/subcellular
Figueroa et al. 1993 [35]	3rd, “term”	no	Carpenter and Coustan	no	no	vascular function
Ganer Herman et al. 2018 [36]	3rd, at delivery	yes	ACOG	yes	no	placental size
Georgiadis et al. 2014 [37]	2nd, 3rd, at delivery	yes	75g OGTT (fasting ≥ 4.8 mmol/l (until 2008) or ≥ 5.3 mmol/l (since 2009), ≥ 10.0 mmol/l 1h, and ≥ 8.6 mmol/l at 2h	no	no	vascular function
Han et al. 2016 [38]	3rd, at delivery	yes	75g OGTT -fasting glucose >92 mg/dL (5.1 mmol/L); 1h> 180 mg/dL (10.0 mmol/L); 2-h > 153 mg/dL (8.5 mmol/L)	no	no	villous maturation
Heidari et al. 2019 [39]	3rd, >37 weeks	no (not different between groups)	ACOG/ Carpenter and Coustan	matched	no	placental size
Huynh et al. 2015 [40]	3rd	yes	Carpenter and Coustan	no	no	histoarchitecture, villous maturation
Ji et al. 2017 [41]	3rd, at delivery	no	fasting glucose >5.1 mM or 1h OGTT >10.0 mM, or 2h OGTT >8.5 mM.	no	no	cellular/subcellular
Jones et al. 1976 [42]	3rd, >37 weeks	no	not specified	no	no	histoarchitecture
Jones et al. 1993 [43]	3rd, >37 weeks	no	not specified	no	no	vascular function
Kleiner et al. 2020 [44]	3rd, at delivery	no	ACOG	no	no	histoarchitecture
Kovo et al. 2016 [45]	3rd, “term”	no	ADA	matched	yes	placental size, histoarchitecture, villous maturation
Kozłowska-Rup et al. 2014	not specified	no	WHO	operative	A1 only	cellular/subcellular
Lao et al. 1997 [46]	3rd, at delivery	no	WHO (1980)	no	no	placental size
Lao et al. 2001 [47]	3rd, at delivery	no (groups not different)	WHO	no	no	placental size
Loegl et al. 2017 [48]	3rd, at delivery	yes	75 g OGTT, two or more >92 g/l fasting, >180 g/l 1 h, >153 g/l 2 h	no	no	vascular function
Magee et al. 2014 [49]	at delivery	no	ADA	operative	no	cellular/subcellular
Makhseed et al. 2004 [50]	3rd, at delivery	no	75g OGTT fasting >5.3 mmol/L or 2h >8.5 mmol/L	no	no	placental size
Mando et al. 2018 [51]	3rd, “term”	yes	OGTT (not otherwise specified)	operative	no	cellular/subcellular
Mayhew 1998 [52]	1st, 2nd, 3rd	no	not specified	no	yes	villous maturation, vascular function
Mayhew and Sisley 1998 [53]	3rd, >37 weeks	controlled	not specified	no	yes	placental size, fibrin deposition
McNamara et al. 2014 [54]	3rd, >37 weeks	yes	not specified	yes	no	placental size
Memon et al. 2015 [55]	3rd, “term”	no	not specified	no	no	placental size, histoarchitecture, fibrin deposition
Meng et al. 2015 [56]	3rd, “term”	no	ADA	operative	no	histoarchitecture, villous maturation, villous edema, fibrin deposition
Pala et al. 2016 [57]	2nd, 3rd	no	WHO	no	no	placental size, histoarchitecture
Pathak et al. 2010 [58]	3rd, >37 weeks	no	WHOhis	no	no	placental size
Pathak et al. 2011	3rd, >34 weeks	no	WHO	no	no	histoarchitecture
Patil et al. 2019 [59]	2nd, 3rd	no	Diabetes in Pregnancy Study group India (DIPSI)	no	no	villous maturation
Pavlova et al. 2020 [60]	not specified	no	not specified	no	no	histoarchitecture
Perovic et al. 2012 [61]	2nd, 3rd > 24 wks	no	ADA	not applicable	no	placental size, vascular function
Ramos et al. 2016 [62]	at delivery, ≥23 weeks	yes	NDDG	no	yes	placental size
Razak et al. 2018 [63]	3rd, >37 weeks	no	fasting ⩾5.6mmol/L or a 2h ⩾7.8mmol/L	operative	no	vascular function
Saha et al. 2014 [64]	3rd, at delivery	No	fasting glucose >126 mg/dl, random >200 mg/dl, or 100g OGTT	no	no	placental size, villous edema, fibrin deposition, vascular function
Sak et al. 2013 [65]	3rd, >28 weeks	no	not specified	no	no	histoarchitecture, villous edema, fibrin deposition
Salafia et al. 1989 [66]	3rd, >37 weeks	no	not specified	no	no	placental size vascular function
Samuel et al. 2014 [67]	3rd, “term”	no	fasting glucose ⩾92mg/dL and 1 h ⩾ 180mg/dL and 2 h ⩾ 153mg/dL	vaginal	no	vascular function
Schönfelder et al. 1996 [68]	3rd, “term”	no	NDDG criteria	no	no	vascular function
Scifres et al. 2017 [69]	3rd, at delivery	yes	Carpenter-Coustan	no	no	vascular function
Sharma S.et al. 2014 [70]	3rd, >36 weeks	no	fasting >90mg/dL or random >105 on first visit plus screening at 12–13 wks and 24–28 weeks	no	no	fibrin deposition, villous immaturity
Soygur et al. 2016 [71]	1st (4–9w) and at delivery (not specified)	yes	fasting glucose >92 mg/dl, 75g OGTT 1 hour >180 mg/dl, and 2 hours >153 mg/dl	operative	A2 only	cellular/subcellular
Stanek et al. 2007 [72]	2nd,3rd	no	not specified	no	no	histoarchitecture
Stanek et al. 2014 [73]	2nd, 3rd	no	not specified	no	no	histoarchitecture
Stoz et al. 1988 [74]	3rd, >37 weeks	no	100g OGTT (J.B O’Sullivan criteria)	no	no	villous maturation, vascular function
Strøm-Roum et al. 2016 [75]	3rd, at delivery	yes	2-h 75-g OGTT with glucose ≥7.8 to <11.1 mmol/L	no	no	placental size
Surányi et al. 2016 [76]	2nd, 3rd, 15–28 weeks	no	WHO	not applicable	no	placental size
Taricco et al. 2009 [77]	3rd, at delivery	no	ACOG/ Carpenter and Coustan	operative only	no	placental size
Taricco et al. 2003 [78]	3rd, >36 weeks	no	ACOG/ Carpenter and Coustan	no	no	placental size
Thunbo et al. 2018 [79]	3rd, >35 weeks	yes	not specified	no	no	placental size
Tramontana et al. 2018 [80]	1st	yes	IADPSG	no	no	vascular function
Vilariño-García et al. 2016 [81]	3rd, “term”	no	ADA	operative only	no	placental size
Visiedo et al. 2017 [82]	3rd, “term”	no	NDDG (1979)	operative only	no	cellular/subcellular
Wang et al. 2019 [83]	3rd, “term”	no	fasting >92 mg/dl and 1h >180 mg/dl or 2h >153 mg/dl on OGTT	no	no	vascular function, cellular/subcellular
Wong et al. 2019 [84]	1st, 2nd	no	National Diabetes Data Group Criteria	no	no	placental size, vascular function
Yavuz et al. 2015 [85]	3rd, “term”	no	OGTT ≥140 mg/dL	no	no	histoarchitecture
Younes et al. 1996 [86]	3rd, >37 weeks	no	not specified	no	no	villous maturation
Yuksel et al. 2016 [87]	3rd	yes	ACOG/Carpenter and Coustan	no	yes	Histoarchitecture, vascular function
Zhou et al. 2016 [88]	3rd, >37 weeks	no	WHO/IADPSG	operative only	no	vascular function