Characteristics of included SRs
| Ref. | Year | Population | Intervention/ exposition | Comparison | Outcomes | Included studies | Critical appraisal of study or reporting quality | |||
| ∑ | Designs | Published | Setting | |||||||
| SR without meta-analysis | ||||||||||
| Rashidian et al18 | 2014 | Term and preterm birth | Perinatal regionalisation | Historical or concurrent control groups, comprised of usual care services (ie, no perinatal regionalisation) | Mortality (neonatal, perinatal, maternal), morbidit, birth weight, stillbirth, place of delivery | 8 | 3 ITS | 1979–2007 | 6 USA | Risk of bias criteria for EPOC reviews |
| 1 CBA | 1 FR | |||||||||
| 4 BA | 1 CA | |||||||||
| Neogi et al19 | 2012 | Term and preterm birth | Perinatal regionalisation | Not born in level III centres | Neonatal and perinatal mortality | 17* | 1 PC | 1979–2001 | 13 USA | MOOSE guidelines (no results provided) |
| 2 BA | 2 CA | |||||||||
| 1 UK | ||||||||||
| 14 RC | 1 POR | |||||||||
| Unit size/ case-volume | Units, <1500 term births or <100 VLBW annually | 6 | 6 RC† | 1983–2006 | 3 USA | |||||
| 2 NO | ||||||||||
| 1 GER | ||||||||||
| SR with meta-analysis | ||||||||||
| Lasswell et al20 | 2010 | Liveborn VLBW (≤1500 g), VPT (≤32 weeks’ GA) born ≥1976 | Perinatal regionalisation | Births at facilities with lower designated level of care, regardless of subsequent transfer | Neonatal mortality or pre-discharge/ in-hospital mortality | 12 | 9 RC | 1982–2008 | 8 USA | Unreferenced own quality assessment (no results provided) |
| 1 PC | 1 USA and EU | |||||||||
| 1 C–C | 1 CA | |||||||||
| 1 RCT | 1 SWE | |||||||||
| 1 NL | ||||||||||
*The review authors reported the results of 13 studies; for four studies, the authors of this umbrella review extracted these missing results.
†Categorised by authors of the present umbrella review due to a lack of described study designs.
BA, before–after; CA, Canada; CBA, controlled before–after; C–C, case–control; EPOC, Cochrane's Effective Practice and Organisation of Care; EU, Europe; FR, France; GA, gestational age; GER, Germany; ITS, interrupted time series; MOOSE, Meta-analysis Of Observational Studies in Epidemiology; NL, Netherlands; NO, Norway; PC, prospective cohort; POR, Portugal; RC, retrospective cohort; RCT, randomised controlled trial; SR, systematic review; SWE, Sweden; VLBW, very low birth weight; VPT, very preterm.