Effects of an early water, sanitation, hygiene, and nutritional intervention on child development at school age: a 7-year follow-up of a cluster-randomized trial in rural Bangladesh

BackgroundA previous cluster-randomized controlled trial in Bangladesh found that individual or combined water, handwashing, sanitation, and nutrition interventions during pregnancy and after birth improved developmental outcomes of children at 1 and 2 years of age. We aimed to determine if these intervention effects were sustained at school-age. Methods and FindingsPregnant women were enrolled between May 2012 and July 2013 and randomized into chlorinated drinking water (W); improved sanitation (S); handwashing with soap (H); combined WSH; nutrition counselling and provision of lipid-based supplements (N); combined WSH+N, or a passive control arm (C) (N=5,551). We followed-up enrolled mothers and children 5 years after intervention completion. Primary outcomes were child cognition, fine motor abilities, behaviour, school achievement, and executive function; secondary outcomes were maternal mental health and the home environment. We conducted intention to treat analyses using generalized linear models to determine unadjusted and adjusted comparisons between each arm and the control, accounting for pair-matching and block level clustering. Between September 2019 and February 2021, we re-enrolled 3,832 children. Children in the WSH+N, N, and S arms had improved cognitive scores on one or more domains compared to the control arm, with adjusted effect sizes between 0.10 (95%CI: 0.00, 0.20) and 0.15 (0.03, 0.27). Children in all arms except S had improved prosocial behaviour, with effect sizes between 0.21 (0.07, 0.34) and 0.33 (0.17, 0.49). No intervention effects were observed for fine motor, difficult behaviours, executive functioning, or school achievement. Maternal depressive symptoms were improved in the WSH+N, H, and N arms, and the stimulating home environment was improved in all intervention arms. Data collection for this study was interrupted by a 6-month pause at the start of the COVID-19 pandemic. ConclusionsAt 7 years of age, we found small, sustained impacts of early water, sanitation, hygiene, and nutrition interventions on child cognitive and social-emotional outcomes, the stimulating home environment, and maternal mental health. Future work to determine the mechanisms underlying these intervention effects will further inform the design of early interventions to improve child health and development. Trial registrationFollow-up trial: ClinicalTrials.gov, NCT04443855 Original WASH-Benefits Bangladesh (WASH-B): ClinicalTrials.gov, NCT01590095