Barber 2008.

Methods	Parallel‐arm cluster‐RCT conducted at 506 sites in Mexico between 1997 and 2003.
Participants	Sample size: 506 clusters randomised (individuals not reported), 173 clusters analysed. Clusters: "The rural programme established eligibility in two stages: poor communities were first identified, and low‐income households were identified within those communities". Communities and households were randomly selected based on a probability sample proportionate to the number of women of reproductive age women (15–49 years). Individuals: the sample included women who experienced a singleton live birth between 1997 and 2003, were designated as poor and eligible for Oportunidades, and lived in the original treatment and control communities
Interventions	Target: community (financial incentive intervention). Arm 1 (97 clusters, 810 women): Progresa or Opportunidades is a conditional cash transfer program established in 1997 in Mexico, with the dual aim of immediate poverty relief and long‐term impact on the generational transfer of poverty. Every 2 months intervention families received a cash transfer representing approximately a 25% increase in household income (Gertler 2000, p. 3). The cash transfer required specific health behaviours of all members of households. Pregnant women were required to have 5 prenatal visits beginning in the first trimester of pregnancy. Beneficiary births are those births that occurred after the household received their first cash transfer. Households in intervention areas began receiving benefits during the summer of 1998. Arm 2 (61 communities, 215 women): non‐beneficiary births are those that occurred among eligible women prior to receiving the first cash transfer. Households in control clusters began receiving benefits in November 1999.
Outcomes	Trial primary outcome: birthweight. Review outcomes reported: Primary: ANC coverage (at least 4 visits). Secondary: at least 1 ANC visit, health facility deliveries, tetanus protection, low birthweight infants. Follow‐up: once.
Notes	The Mexican social welfare program Oportunidades (now Prospera) has multiple citations. We have incorporated data from a specific analysis conducted on a small sample of women in households involved in this large poverty relief program (Barber 2008). Funders: National Institutes of Health Fogarty International Center TW006084 and National Institute of Child Health and Human Development.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	For the initial cluster‐randomisation, "random assignment was generated at the community level without weighting by use of the randomisation commands in Stata version 2.0" (Fernald 2008). For the survey, areas were randomly assigned "based on a probability sample proportionate to the number of women of reproductive age". p. 20 Barber 2009.
Allocation concealment (selection bias)	Unclear risk	Not reported.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Due to the nature of the intervention participants could not be blinded.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Recruitment bias (for cluster RCTs)	Low risk	None noted.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Loss to follow‐up described but sample sizes vary in the different reports.
Selective reporting (reporting bias)	Low risk	Most relevant outcomes reported.
Analysis bias	Low risk	Analysis appropriate for clusters; ITT analysis performed.
Other bias	Low risk	No baseline imbalances.
Overall risk assessment	Low risk	No serious risk of bias concerns.