Table 2.
Characteristics of the studies included in the meta-analysis
| Study ID | Country | Study period | Study design | Population | Size | First two births | Risk adjustment* |
|---|---|---|---|---|---|---|---|
| Singh_1981 | India | 1973-1978 | Cohort | Hospital | 12040 | 0 | - |
| Gorodeski_1985 | Israel | 1972-1983 | Case-control | Hospital | 455 | 0 | - |
| Sauer_1985 | USA | 1981-1984 | Case-control | Hospital | 135 | 0 | - |
| Clark_1985 | USA | 1977-1983 | Cohort | Hospital | 97799 | 0 | - |
| Rose_1986 | England | 1978-1982 | Case-control | Hospital | 160 | 0 | AP; |
| Hemminki_1987 | Sweden | Cohort | Population | 7337 | 1 | AP; | |
| Nielsen_1989 | Sweden | 1978-1987 | Cohort | Hospital | 24644 | 0 | - |
| Williams_1991 | USA | 1977-1980 | Case-control | Hospital | 12420 | 0 | AP; abortion; alcohol and tobacco use; SE |
| Chattopadhyay_1993 | Saudi Arabia | 1988-1992 | Cohort | Hospital | 41206 | 0 | - |
| Zhang_1993 | USA | 1988-1990 | Case-control | Population | 6478 | 0 | - |
| Parazzini_1994 | Italy | 1979-1991 | Case-control | Hospital | 203 | 0 | - |
| Makhseed_1994 | Kuwait | 1992-1992 | Cohort | Hospital | 8721 | 0 | - |
| Khouri_1994 | Saudi Arabia | 1985-1989 | Cohort | Hospital | 25551 | 0 | - |
| Taylor_1994 | USA | 1984-1987 | Case-control | Population | 1967 | 0 | AP; abortion; tobacco use |
| To_1995 | Hong Kong | 1984-1993 | Cohort | Hospital | 50485 | 0 | - |
| Monica_1995 | Sweden | 1983-1990 | Case-control | Population | 4676 | 0 | AP; previous previa |
| Hemminki_1996 | Finland | 1987-1993 | Cohort | Population | 10889 | 1 | AP; provider |
| Chelmow_1996 | USA | 1992-1994 | Case-control | Hospital | 128 | 0 | - |
| Takayama_1997 | Japan | 1974-1994 | Case-control | Hospital | 264 | 0 | - |
| Macones_1997 | USA | 1992-1996 | Case-control | Hospital | 120 | 0 | age; abortion; drug and tobacco use |
| Ziadeh_1999 | Jordan | 1995-1996 | Cohort | Hospital | 18651 | 0 | - |
| Hendricks_1999 | Singapore | 1993-1997 | Cohort | Hospital | 16169 | 0 | - |
| Rageth_1999 | Switzerland | 1983-1996 | Cohort | Population | 255453 | 0 | - |
| Archibong_2001 | Saudi Arabia | 1997-2002 | Cohort | Hospital | 15191 | 0 | - |
| Lydon-Rochelle_2001 | USA | 1987-1996 | Cohort | Population | 95630 | 1 | AP |
| Eniola_2002 | Nigeria | Case-control | Hospital | 272 | 0 | AP; abortion; SE | |
| Gilliam_2002 | USA | 1986-1989 | Case-control | Hospital | 1171 | 1 | AP; abortion; tobacco use |
| Tuzovic_2003 | Croatia | 1992-2001 | Case-control | Hospital | 1206 | 0 | - |
| Hossain_2004 | Bangladesh | 2000-2002 | Cohort | Hospital | 2536 | 0 | - |
| Olive_2005 | Australia | 1998-2002 | Cohort | Hospital | 375653 | 0 | - |
| Getahun_2006 | USA | 1989-1997 | Cohort | Population | 156475 | 1 | AP; abortion; alcohol and tobacco use; prenatal care; inter pregnancy interval; SE |
| Kennare_2007 | Australia | 1998-2003 | Cohort | Population | 36038 | 1 | AP; abortion |
| Hung_2007 | Taiwan | 1990-2003 | Cohort | Hospital | 37702 | 0 | - |
| Daltveit_2008 | Norway | 1967-2003 | Cohort | Population | 637497 | 1 | AP; delivery date |
| Rahim_2009 | Pakistan | 2001-2005 | Cohort | Hospital | 20110 | 0 | - |
| Yang_2009 | USA | 1995-2000 | Cohort | Population | 11026768 | 0 | AP; abortion; alcohol, tobacco and drug use; prenatal care; SE |
| Rosenberg_2010 | Israel | 1988-2009 | Cohort | Hospital | 185476 | 0 | AP; abortion; fertility treatment; tobacco use |
* AP: age and parity; SE: socioeconomic factors