Table 1

Description of included studies

Study NoReferenceCountrySettingStudy designStudy periodParticipantsNumber of participantsInterventionComparison groupsOutcomes
RCT
1Chambliss et al23USAOne university hospitalRCTUnknownLow-risk pregnancyTotal: 487
P0: 116
P+: 371		Birth centre managed by nurse-midwivesDelivery unit managed by physicians

  • Mode of delivery

  • Length of labour

  • Apgar scores

  • Birth weight

  • Use of episiotomy

2Law and Lam24Hong Kong, ChinaOne tertiary hospitalRCTNovember 1994–June 1995Risks manageable by midwivesTotal: 1050
P0: 532
P+: 518		Midwife-managed birth careStandard care

  • Events during labour

  • Modes of delivery

  • Neonatal outcomes

3Bernitz et al25 26NorwayOne secondary hospitalRCT2006–2010Low-risk pregnancyTotal: 1111
P0: 747
P+: 364		Midwife-led unitStandard obstetric unit (combined normal and special units)

  • Operative delivery rate

  • Maternal and neonatal outcome

  • Cost per patient

  • Cost-effectiveness

CBA
4Hofmeyr et al27South AfricaOne tertiary hospitalCBA2011–2013Women giving birth in the hospital*Total: 13 727
P0: Unknown
P+: Unknown		Midwife-led birth unit

  • Obstetric unit;

  • Before and after intervention

  • Caesarean section rate

  • Maternal mortality

  • Perinatal mortality

Cohort
5Homer et al28AustraliaOne tertiary hospitalRetrospective cohort1995Low-risk pregnancy†Total: 734
P0: Unknown
P+: Unknown		Birth centre managed by midwifeLabour ward

  • Mode of delivery

  • Analgesia in labour

  • Perineal outcomes

  • Neonatal outcomes

6Rana et al29NepalOne district hospitalProspective cohortNovember 1997–February 1998Low-risk pregnancy‡Total: 988
P0: Unknown
P+: Unknown		Midwifery unitConsultant-led unit

  • Intrapartum complications and procedure

  • Mode of delivery

  • Perinatal outcomes

7Eide et al30§NorwayOne university hospitalProspective cohortNovember 2001–May 2002Low-risk primiparous women¶Total: 453Midwife-led wardConventional delivery ward

  • Intrapartum interventions

  • Neonatal outcomes

8Suzuki et al31; Suzuki32JapanMaternity hospitalRetrospective cohort2008–2010Low-risk pregnancy**Total: 1031
P0: 506
P+: 525		Midwife-led careObstetric shared care

  • Obstetric outcome

  • Neonatal outcome

9Cheung et al33 34††ChinaOne tertiary hospitalRetrospective cohortMarch–September 2008Low-risk pregnancy‡‡Total: 452
P0: 425
P+: 27		Midwife-led unitStandard labour ward

  • Mode of delivery

  • Augmentation of labour

  • Pain management

  • Birth companion

  • Neonatal outcomes

  • Satisfaction of women and midwives

10Brocklehurst et al35 §§;
Schroeder et al36		UKNationwideProspective cohort2008–2010Low-risk pregnancy¶¶Total: 64 538
P0: 28 443
P+: 35 289		Alongside midwifery unit

  • Obstetric unit

  • Freestanding midwifery unit

  • Home delivery

  • Perinatal mortality and morbidity

  • Mode of birth

  • Maternal interventions

  • Costs of delivery

  • Cost-effectiveness

  • *No information on maternal characteristics were available.

  • †Women were of similar age and parity in the intervention and comparison groups; no information on other maternal characteristics was available.

  • ‡Women were a similar age in the intervention and comparison groups; the socioeconomic status (defined by the study authors) of the comparison group was slightly higher than that of the intervention group.

  • §Adjusted for maternal age, smoking, education and marital status.

  • ¶Women were a similar age in the intervention and comparison groups, but there were significant differences in marital status, maternal education, working during pregnancy and smoking habits between the two groups.

  • **Women were a similar age in the intervention and comparison groups; there were more primiparous women in the comparison group. No information on other maternal characteristics was available.

  • ††Mixed quantitative and qualitative methods were used for data collection

  • ‡‡Women were a similar age in the intervention and comparison groups; no information on other maternal characteristics was available.

  • §§Adjusted for maternal age, ethnic group, understanding of English, marital or partner status, body mass index in pregnancy, index of multiple deprivation score, parity and gestational age at birth

  • ¶¶The characteristics of women in the alongside midwifery unit group were generally similar to those of the obstetric unit group.

  • CBA, controlled before-and-after study; P0, nulliparous women; P+, multiparous women; RCT, randomised controlled trial.