Acute malnutrition affects 52 million children, costs $2.1 trillion globally, and contributes to 45% of deaths among children under five years of age. Affordable home-based treatments can prevent many of these deaths, with success rates over 97.5% if malnutrition is identified early. If identified late, treatment failure rates increase to 16%. Malnutrition programs currently rely on community health volunteers to screen children, which can lead to high costs, low screening coverage, and late identification. Mid upper arm circumference (MUAC) is the preferred community malnutrition screening tool. Training mothers to use MUAC tapes to monitor their child's nutritional status through a short message service (SMS) mobile health system could increase screening coverage and facilitate rapid engagement with nutritional services where necessary. The investigators propose to test the "Maternal Administered Malnutrition Monitoring System" (MAMMS) in a randomized controlled trial in Kenya. Participants will be taught to measure their child's MUAC at 6 or 9-month immunization visits and during 6-month follow up the participants will receive a weekly SMS prompting them to measure and send their child's MUAC to a computer system which will alert a health worker when a child with malnutrition is identified. This scalable system could enable nutrition programs to optimize screening coverage, leading to early identification of malnutrition, lower costs and a reduction in under-five mortality.

Acute malnutrition is a critical driver of pediatric mortality that must be addressed to achieve global child health targets. Provision of ready-to-use therapeutic foods (RUTF) and nutritional counselling in the community is a highly effective method of preventing deaths among malnourished children. However, UNICEF estimates that only 17% of malnourished children receive treatment. Among children who are treated, the diagnosis of acute malnutrition is often made late in their disease when the risk of complications and death increases from 2.5% to 16%. Increasing the coverage and frequency of nutritional screening to identify malnourished children earlier in the disease process is a critical step toward achieving global child health goals.

Mid-upper arm circumference (MUAC) is the preferred community malnutrition screening tool. Recent evidence comparing MUAC measurements taken by mothers and community health workers showed that mothers can accurately measure their child's MUAC and identify malnutrition. Yet, there is no pragmatic method of linking these mothers to the nutritional care that malnourished children require. Training and supporting mothers to use MUAC tapes to monitor their child's nutritional status through a two-way short message service (SMS) mobile health system could dramatically increase the coverage of malnutrition screening and facilitate rapid engagement with nutritional service where necessary.

This randomized controlled trial will test the "Maternal Administered Malnutrition Monitoring System" (MAMMS) in western Kenya. Participants will be taught to measure their child's MUAC at 6 or 9-month immunization visits and during 6-month follow up participants will receive weekly SMS messages prompting them to measure and send their child's MUAC to a computer system which will alert a health worker when a child with malnutrition is identified. This scalable childhood growth monitoring system could enable nutrition programs in low and middle income countries to optimize screening coverage, leading to early identification of malnutrition, lower costs and a reduction in global under-five mortality. The study aims to:

Aim 1: Determine if MAMMS leads to earlier identification and recovery from acute malnutrition (MUAC <12.5cm).

Hypothesis 1.1: Children randomized to MAMMS who develop acute malnutrition will be identified earlier than children in the control arm.

Hypothesis 1.2: Children randomized to MAMMS who develop acute malnutrition will be more likely to successfully complete nutritional rehabilitation (defined as no death, no hospitalization, no severe acute malnutrition, and resolution of moderate malnutrition within 4 months of diagnosis) than children in the control arm diagnosed with acute malnutrition.

Aim 2: Demonstrate the accuracy of maternal administered MUAC assessments compared to trained community health worker, and the ability of repeated maternal administered MUAC measurements to monitor early childhood growth.

Hypothesis 2.1: Maternally measured MUAC will be strongly correlated with health worker measured MUAC at baseline and during follow-up.

Hypothesis 2.2: A highly sensitive and specific growth trajectory that predicts moderate acute malnutrition can be identified using maternally measured MUAC.

Aim 3: Evaluate the acceptability, feasibility, fidelity and cost per-child-treated of MAMMS relative to standard-of-care nutrition programs.

Hypothesis 3.1: MAMMS will be acceptable and feasible to mothers and health workers.

Hypothesis 3.2: MAMMS will have a substantially lower cost-per-malnutrition case identified than standard screening approaches.

Inclusion Criteria:

• Infant is 6-12 months of age and MUAC of 12.5-14.0 cm
• Access to a mobile phone and can provide a mobile phone number
• Planning to remain in the catchment area more than 6 months and willing to return for 6-month follow up visit
• Mother is willing to be randomized to weekly SMS and measure and send weekly infant MUAC via SMS
• Able to read or write or has someone to help them read or write

Exclusion Criteria:

• Infant is currently on treatment for malnutrition
• Inability to provide a mobile phone number
• Mothers that could not read or write and did not have someone to help them read or write

IPD that underlie results in a publication will be shared with other researchers.

IPD that underlie results in a publication will be made publicly available within 6 months of the publication.

IPD that underlie results in a publication will be made publicly available in an open access repository within 6 months of the publication.