Table 1. Selected characteristics of the studies included in this systematic review and meta-analysis.
| Source | Country | Survey Period | Cases | Total | Prevalence (%)[95% CI] | Age (year)* | GA (week)* | AP | PCS | MP | Study | QS |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wortman AC29 | USA | 2002–2012 | 71 | 98 | 72.4 (63.6,81.3) | 30.8 ± 6.1 | 38.1 ± 2.3 | 18 | 21 | 80 | Rep | 8 |
| Shin JE16 | Korea | 2010–2014 | 49 | 93 | 52.7 (42.5,62.8) | 35.5 ± 4.2 | 37.0 ± 2.4 | 14 | 23 | 53 | Rep | 7 |
| Kollmann M36 | Austria | 1993–2012 | 68 | 328 | 20.7 (16.3,25.1) | 31.6 (17–46) | 35.6 (23–41) | — | — | 187 | Pro | 8 |
| Goto M17 | Japan | 2009–2014 | 55 | 99 | 55.6 (45.8,65.3) | 35.5 (25–49) | — | 15 | 15 | 49 | Pro | 8 |
| Sekiguchi A28 | Japan | 2004–2012 | 58 | 162 | 35.8 (28.4,43.2) | 33.5 ± 4.4 | 37.4 (17–38) | 31 | 19 | 94 | Rep | 9 |
| Curti A30 | USA | 2001–2010 | 17 | 43 | 39.5 (24.9,54.1) | 33.8 (25–44) | 37.1 (28–40) | — | 11 | 22 | Rep | 7 |
| Giambattista E37 | Italy | 2006–2010 | 79 | 247 | 32.0 (26.2,37.8) | 35.5 ± 4.8 | — | — | 51 | — | Rep | 6 |
| Fukushima K18 | Japan | 2006–2010 | 33 | 80 | 41.2 (30.5,52.0) | 33.5 (23–43) | 37.0 (28–38) | 5 | 12 | — | Rep | 6 |
| Fishman SG31 | USA | 2002–2010 | 51 | 113 | 45.1 (36.0,54.3) | — | 36.0 (34–37) | 33 | 19 | 66 | Rep | 6 |
| Zaitoun MM40 | Egypt | 2008–2010 | 22 | 65 | 33.8 (22.3,45.3) | 31.3 ± 4.4 | 34.2 ± 2.4 | — | 21 | 22 | Rep | 6 |
| Suknikhom W19 | Thailand | 2006–2008 | 110 | 206 | 53.4 (46.6,60.2) | 33.4 ± 4.6 | — | 71 | 39 | 99 | Rep | 8 |
| Mimura T20 | Japan | 2000–2008 | 67 | 115 | 58.3 (49.2,67.3) | 33.4 ± 4.3 | 35.2 ± 2.4 | 9 | 12 | — | Rep | 7 |
| Hasegawa J21 | Japan | 2000–2009 | 102 | 182 | 56.0 (48.8,63.3) | 33.6 (23–43) | 36 (22–37) | 24 | — | — | Rep | 7 |
| Stafford IA32 | USA | 2007–2009 | 32 | 68 | 47.1 (35.2,58.9) | 31.9 ± 5.8 | — | 32 | 35 | 63 | Rep | 8 |
| Vergani P10 | Italy | 2003–2008 | 19 | 95 | 20.0 (12.0,28.0) | 34.2 ± 4.1 | 36.8 ± 3.6 | 46 | — | 49 | Rep | 9 |
| Ghi T38 | Italy | 2005–2007 | 29 | 60 | 48.3 (35.7,61.0) | 34.9 ± 4.5 | 34.7 ± 2.3 | — | 49 | 31 | Pro | 8 |
| Bahar A22 | Saudi Arabia | 1996–2005 | 236 | 306 | 77.1 (72.4,81.8) | 30.6 (16–49) | — | — | 165 | — | Rep | 6 |
| Oya A23 | Japan | 1993–2007 | 66 | 129 | 51.2 (42.5,59.8) | 32.1 ± 5.0 | 35.9 ± 2.9 | — | 16 | 66 | Rep | 7 |
| Matsubara S24 | Japan | 1994–2005 | 18 | 73 | 24.7 (14.8,34.5) | 31.4 (28–34) | 37 (36–39) | — | 9 | 36 | Rep | 7 |
| Tuzovic L11 | Croatia | 1992–2001 | 181 | 202 | 89.6 (85.4,93.8) | — | — | 65 | 20 | 146 | Rep | 8 |
| Love CD39 | UK | 1994–2000 | 129 | 161 | 80.1 (74.0,86.3) | — | 36.4 ± 5.9 | — | — | — | Rep | 7 |
| Bhat SM15 | Oman | 1998–2002 | 35 | 58 | 60.3 (47.8,72.9) | 30.6 ± 5.9 | 35.0 ± 3.4 | — | 8 | 48 | Rep | 7 |
| Ogueh O33 | Canada | 1997–1999 | 162 | 703 | 23.0 (19.9,26.2) | 31.3 ± 4.8 | 39.4 ± 1.8 | — | 81 | — | Rep | 6 |
| Dola CP34 | USA | 1990–1997 | 137 | 175 | 78.3 (72.2,84.4) | 30.8 ± 5.7 | 35.3 ± 3.5 | 62 | 68 | — | Rep | 9 |
| Ghourab S25 | Saudi Arabia | 1995–2000 | 37 | 71 | 52.1 (40.5,63.7) | 29.5 ± 3.8 | 35.2 ± 4.3 | 40 | — | — | Pro | 7 |
| Lam CM26 | China | 1991–1997 | 159 | 252 | 63.1 (57.1,69.1) | 31.5 ± 4.6 | 32.6 ± 4.9 | — | 32 | — | Rep | 8 |
| Crane JM5 | Canada | 1988–1995 | 205 | 308 | 66.6 (61.3,71.8) | 30.0 | — | — | — | 234 | Rep | 7 |
| Dawson WB35 | Canada | 1991–1993 | 21 | 40 | 52.5 (37.0,68.0) | 29.0 ± 5.0 | — | — | — | — | Rep | 6 |
| Gorodeski IG27 | Israel | 1973–1983 | 99 | 155 | 63.9 (56.3,71.4) | — | — | — | 18 | — | Rep | 7 |
AP: placenta on anterior wall; GA: gestational age; MP: multiperous; PCS: previous cesarean section; Pro: prospective cohort study; QS: quality score; Rep: retrospective cohort study.
*Values indicate the mean (range), or mean ± standard deviation.