Characteristics of included studies
| Study ID author, year, country | Design | Sample size | Time period | Inclusion criteria | Data source | Trimester | Seat belt use (with data) | Assessment of trauma severity (with data) | Method of assessing trauma severity | Maternal outcomes | Offspring outcomes |
| Population-level data | |||||||||||
| Azar et al,2 2015, USA | Population-based matched retrospective cohort (incidence only) | 5936 | 2003–2011 | Admitted to hospital following MVC while pregnant | Population-based cohort | Any | No | No | N/A | Maternal death | – |
| Hyde et al,26 2003, USA | Retrospective cohort (incidence and comparison) | 322 704 | 1992–1999 | Pregnant drivers involved in MVC | Linked databases (police registry and birth/death certificates) | Any | Yes | Yes | Study-specific definition‡ | – | Fetal death |
| Kvarnstrand et al,27 2008, Sweden | Retrospective cohort (incidence and comparison) | 1 094 559 | 1991–2001 | Maternal inclusion on the accident register >28 GW | Linked databases (police registry and birth/death certificates) | 2nd | No | Yes | Study-specific definition§ | Maternal death | Fetal/neonatal death |
| Kuo et al,33 2007, USA | Retrospective chart/database review (incidence only) | 16982 injuries 4479 (in MVC) | 2002 | Pregnant women hospitalised with injury (only MVC used) | Sample from population level cohort (National Inpatient Sample) | Any | No | No | N/A | Delivery, hospitalisation | – |
| Schiff and Holt,28 2005, USA | Retrospective cohort (incidence and comparison) | 17 899 | 1989–2001 | Hospitalised for MVC and with a singleton live birth or fetal death | Linked databases (hospital discharge data and birth/death certificates) | Any | No | Yes | ISS | Preterm birth, PROM, C-section, placental abruption | Stillbirth, LBW, SGA, fetal distress, RDS, meconium |
| Schiff et al,36 2010, USA | Retrospective cohort (incidence only) | 3348 | 2002–2005 | Non-rollover MVC among pregnant front seat occupants | Linked databases (hospital discharge data and birth/death certificates) | Any | Yes (airbag); no (seat belt) | No | N/A | Preterm birth, placental abruption, labour induction, C-section | Stillbirth, LBW, SGA, RDS, fetal distress, meconium |
| Vivian-Taylor et al,6 2012, Australia | Retrospective cohort (incidence and comparison) | 604 380 | 2000–2007 | Women who gave birth exposed and not exposed to MVC | Linked databases (hospital discharge data and birth/death certificates) | 2nd | No | Yes | Study-specific definition¶ | Admission, placental abruption, APH, PPH, preterm birth, C-section | Perinatal death (>20th GW), neonatal transfer |
| Vladutiu et al,8 2013, USA | Retrospective cohort (incidence and comparison) | 878 546 | 2001–2008 | Pregnant women 16–46 years, >20 GW, delivering a live/stillbirth singleton infant | Linked databases (police registry and birth/death certificates) | 2nd | Yes (seat belt); yes (airbag) | No | N/A | Placental abruption, PROM, preterm birth | Stillbirth |
| Weiss and Strotmeyer,32 2002, USA | Crash database pregnant versus non-pregnant (NASS/CDS) (incidence only) | 32 810 | 1995–1999 | Pregnant and non-pregnant women 15–39 years | Sample from population-level database of traffic accidents | Any | Yes | No | N/A | Maternal death | – |
| Weiss et al,35 2008, USA | Retrospective cohort (incidence only) | 1816 | 1999–2002 | Injury-related emergency department visits by pregnant women (only MVC used) | Linked databases (hospital discharge data and birth/death certificates) | Any | No | No | N/A | Hospital admission | – |
| Whitehead,39 2013,* USA | PRAMS survey database (incidence only) | 235 329 | 2000–2005 | Survey of women who recently delivered a live-born infant | Population-based cohort (PRAMS) | Any | No | No | N/A | Preterm birth, UTI, PROM | – |
| Wolf et al,29 1993, USA | Population-based retrospective cohort (incidence only) | 2582 | 1980–1988 | Pregnant women drivers involved in MVC >20GW | Linked databases (police registry and birth/death certificates) | 2nd and 3rd | Yes | No | N/A | Preterm birth, placental abruption, C-section | Stillbirth, LBW, RDS |
| Single hospital records/trauma registry | |||||||||||
| Aboutanos,34 2007, USA | Retrospective chart/database review (incidence only) | 148 | 2001–2005 | Single hospital records from trauma centre | Any | Yes (only in miscarriage) | Yes | ISS | Maternal death, miscarriage | Fetal death hydrops fetalis | |
| Baerga-Varela et al,30 2000, USA | Retrospective chart/database review (incidence only) | 39 | 1986–1996 | Single hospital records | Any | No | Yes | ISS | Maternal death, miscarriage | Stillbirth | |
| Brookfield et al,37 2013, USA | Retrospective chart/database review (incidence only) | 256 | 1990–2007 | Single hospital records from trauma centre | Any | Yes | Yes | ISS and RTS | Maternal death, admission to hospital | – | |
| Chibber et al,17 2015, Kuwait | Retrospective chart/database review (incidence only) | 728 | 2009–2012 | Single hospital records | 2nd | No | No | N/A | Maternal death, placental abruption, preterm birth, uterine rupture, C-Section, admission | Fetal death, fetal distress | |
| Luley et al,38 2013, USA | Retrospective chart/database review (incidence only) | 126 | 1994–2010 | Single hospital trauma database | 2nd and 3rd | Yes | No | N/A | Maternal death, placental abruption, C-section | Stillbirth | |
| Miller et al,40 2016, Israel | Retrospective cohort (incidence only) | 3794 | 2006–2013 | National trauma registry | Any | No | No | ISS | Maternal death, miscarriage, placental abruption, C-section | Stillbirth | |
| Orji et al,31 2002, Nigeria | Retrospective chart/database review (incidence only) | 84 | 1980–2000 | Single hospital records† | Any | No | No | N/A | Maternal death, placental abruption, uterine rupture, C-section | Perinatal death (fetal death), fetal tachycardia | |
*National survey.
†Two hospitals in same region included.
‡Possible/probable/incapacitated/fatal.
§Fatal/major/minor/uninjured.
¶‘Severe’= admission to ICU and/or blood transfusion and/or injury to abdomen/pelvis/lower back.
APH, antepartum haemorrhage; GW, gestational week; ICU, intensive care unit; ISS, Injury Severity Score; LBW, low birth weight; MVCs, motor vehicle crashes; N/A, not applicable; NASS/CDS, National Automotive Sampling System/Crashworthiness Data System; PPH, postpartum haemorrhage; PRAMS, Pregnancy Risk Assessment Monitoring System; PROM, premature rupture of membranes; RDS, respiratory distress syndrome; RTS, Revised Trauma Score; SGA, small for gestational age; UTI, urinary tract infection.