Table 1.

Characteristics of studies involving universal peer support

Study	Methods	Participants and setting	Intervention	Outcomes	Results	Quality*
MacArthur et al.16	Cluster RCT 66 GPs n = 2511 Intervention: n = 1140 Control: n = 1371	All pregnant women registered with health district remaining in area UK	Routine AN care + 2 AN support sessions with PC (24–38 wk + 32–34 wk)	Primary outcome: BF initiation	Initiation data on 2398 (95%) Intervention: 747/1083 (69.0%) Control: 896/1315 (68.1%) No significant difference	High High High High
Muirhead et al.19	RCT One GP 225 women Intervention: n = 112 Control: n = 113	Pregnant women consented + randomly assigned at 28 wk gestation Scotland, UK	AN PC PN up to 16 wk	BF initiation + duration (up to 6 wk)	Initiation data on 225 (100%) Intervention: 61/112 (54.5%) Control: 60/113 (53.1%) No significant difference	High High High High
Morrow et al.18	Cluster RCT 130 AN recruits Intervention 1: n = 44 Intervention 2: n = 52 Control n = 34	Pregnant women living in and remaining in study area Mexico	Intervention 1: 6 PC home visits (2 AN, 4 PN) Intervention 2: 3 PC home visits (1 AN, 2 PN)	Primary outcome: exclusive BF BF initiation was a baseline factor	Initiation data on 127 (97%) Intervention 1: 44 (100%) Intervention 2: 51 (98%) Control: 32 (94%) No significant difference	High High Medium High
Caulfield et al.15	Cluster RCT 4 WIC practices 548 AN recruits Intervention 1: n = 55 Intervention 2: n = 64 Intervention 3: n = 66 Control: n = 57	Those receiving AN care at one of 4 WIC clinics, singleton pregnancy, not planning on termination, eligible for WIC, planning to remain in clinical catchment area Excluded if BF was contraindicated (HIV infection or medications) USA	Intervention 1: PC only (clinic, home or phone) Intervention 2: motivational videotape in waiting area Intervention 3: PC + motivational videotape in waiting area	BF initiation + continuation to 7–10 days PN	Initiation data on 242 (44%) Intervention 1: 34/55 (62%) Intervention 2: 32/64 (50%) Intervention 3: 34/66 (52%) Control: 15/57 (26%)	Medium Medium Medium Low
McInnes et al.17	Quasi-experiment 995 AN recruits Intervention: n = 474 Control: n = 521	Pregnant women Home town defined whether participants were in intervention or control group Excluded if did not complete pregnancy, had adverse birth outcome, moved from study areas, moved from intervention to control or vice versa, or did not deliver at either hospital linked to these geographic areas Scotland, UK	PC (2 AN + 2 PN sessions)	Infant feeding intention, BF initiation + BF duration (to 6 wk)	Initiation data on 926 (93%) Intervention: 105/449 (23%) Control: 94/477 (20%) p = 0.006	Low Medium Medium High
Shaw et al.21	Retrospective cohort with concurrent control 4 rural WIC counties 93 AN recruits Intervention n = 156 Control n = 135	Women 6 wk–6 mo PN, registered antenatally for WIC-specific health departments. Exclusions: women not seen in AN period by departmental staff Intervention group = women choosing PC. Control group = those who did not want PC + those lacking access to PC USA	PC (1 AN session + PN as required)	BF initiation on hospital discharge + BF duration	Initiation data on 292 (99%) Intervention: 82/156 (53%) Control: 45/135 (33%) p < 0.05	Low Low Medium Low
Schafer et al.20	Prospective cohort WIC clinics in 8 rural counties 207 women recruited Intervention: n = 143 Control: n = 64	AN + PN women qualifying for WIC and referred by WIC clinics Intervention group = AN women requesting PC in 2 counties. Control group = AN + PN women in 6 counties USA	AN + PN PC	BF initiation + BF duration	Initiation data on 207 (100%) Intervention: 117/143 (82%) Control: 20/64 (31%)	Low Low Low Low

Note: AN = antenatal, BF = breastfeeding, GP = general practice, PC = peer counsellor or counselling, PN = postnatal, RCT = randomized controlled trial, WIC = Women, Infants and Children programme.

^*1 = selection bias, 2 = performance bias, 3 = measurement bias, 4 = attrition bias.