10-year effect of Oportunidades, Mexico's conditional cash transfer programme, on child growth, cognition, language, and behaviour: a longitudinal follow-up study

Background Mexico's conditional cash transfer programme, Oportunidades, was started to improve the lives of poor families through interventions in health, nutrition, and education. We investigated the effect of Oportunidades on children almost 10 years after the programme began. Methods From April, 1998, to October, 1999, low-income communities were randomly assigned to be enrolled in Oportunidades immediately (early treatment, n=320) or 18 months later (late treatment, n=186). In 2007, when 1093 children receiving early treatment and 700 late treatment in these communities were aged 8-10 years, they were assessed for outcomes including physical growth, cognitive and language development, and socioemotional development. The primary objective was to investigate outcomes associated with an additional 18 months in the programme. We used cluster-adjusted t tests and multivariate regressions to compare effects of programme participation for height-for-age, body-mass index (BMI), and cognitive language and behavioural assessment scores in early versus late treatment groups. Findings Early enrolment reduced behavioural problems for all children in the early versus late treatment group (mean behaviour problem score -0.09 [SD 0.97] vs 0.13 [1.03]; p=0.0024), but we identified no difference between groups for mean height-for-age Z scores (-1.12 [0.96] vs -1.14 [0.97]; p=0.88), BMI-for-age Z scores (0.14 [0.99] vs 0.17 [1.06]; p=0.58), or assessment scores for language (98.8 [13.8] vs 98.4 [14.6] p=0.90) or cognition (98.8 [12.9] vs 100.2 [13.2]; p=0.26). An additional 18 months of the programme before age 3 years for children aged 8-10 years whose mothers had no education resulted in improved child growth of about 1.5 cm assessed as height-for-weight Z score (beta 0.23 [0.023-0.44] p=0.029), independently of cash received. Interpretation An additional 18 months in the Oportunidades programme has independent beneficial effects other than money, especially for women with no formal education. The money itself also has significant effects on most outcomes, adding to existing evidence for interventions in early childhood.