Effectiveness and co-benefits of a telephone-based intervention in reducing obesity risk of children aged 2–4 years: findings from a pragmatic randomised controlled trial during the COVID-19 pandemic in Australia

BACKGROUND: Evidence of effective early childhood obesity prevention is scarce and mainly derived from face-to-face interventions. However, the COVID-19 pandemic drastically reduced face-to-face health programmes globally. This study assessed effectiveness of a telephone-based intervention in reducing obesity risk of young children. METHODS: We adapted a study protocol (developed before the pandemic) and conducted a pragmatic randomised controlled trial of 662 women with children aged 2 years (mean age 24·06 months [SD 0·69]) during March, 2019, and October, 2021, extending the original planned intervention of 12 months to 24 months. The adapted intervention comprised five telephone-based support sessions plus text messages over a 24-month period (at child ages 24–26 months, 28–30 months, 32–34 months, 36–38 months, and 42–44 months). The intervention group (n=331) received staged telephone plus SMS support regarding healthy eating, physical activity, and information about COVID-19. The control group (n=331) received four staged mail-outs on information not related to the obesity prevention intervention, such as toilet training, language development, and sibling relationships, as a retention strategy. The intervention effects on BMI (primary outcome) and eating habits (secondary outcome), and perceived co-benefits, were evaluated using surveys and qualitative telephone interviews at 12 months and 24 months after baseline (age 2 years). The trial is registered with the Australian Clinical Trial Registry, ACTRN12618001571268. FINDINGS: Of 662 mothers, 537 (81%) completed the follow-up assessments at 3 years, and 491 (74%) completed the follow-up assessment at 4 years. Multiple imputation analysis showed no significant difference in mean BMI between the groups. Among low-income families (ie, annual household income <AU$80 000) at age 3 years, the intervention was significantly associated with a lower mean BMI (16·26 kg/m2 [SD 2·22]) in the intervention group than in the control group (16·84 kg/m(2) [2·37]; p=0·040), a difference of –0·59 (95% CI –1·15 to –0·03; p=0·040). Children in the intervention group were more likely not to eat in front of the television than the control group, with an adjusted odds ratio (aOR) of 2·00 (95% CI 1·33 to 2·99) at 3 years and an aOR of 2·50 (1·63 to 3·83) at 4 years. Qualitative interviews with 28 mothers revealed that the intervention increased their awareness, confidence, and motivation to implement healthy feeding practices, particularly for families from culturally diverse backgrounds (ie, speaking a language other than English at home). INTERPRETATION: A telephone-based intervention was well received by the mothers who participated in the study. The intervention could reduce children's BMI from low-income families. Telephone-based support targeted at low-income families and families from culturally diverse backgrounds could reduce current inequalities in childhood obesity. FUNDING: The trial was funded under the NSW Health Translational Research Grant Scheme 2016 (number TRGS 200) and also by a National Health and Medical Research Council Partnership grant (number 1169823).