Context

Marked social inequalities persist in health outcomes related to diet, physical activity, and sedentary behaviours. These energy balance–related behaviours are socially patterned and contribute to a higher prevalence of obesity among disadvantaged groups, beginning in early childhood. Beyond financial constraints, these disparities stem from structural factors (e.g., availability and accessibility of quality foods) and socio-cultural influences (e.g., perceptions, norms, and practices). However, epidemiological data on the most socially vulnerable populations remain scarce, as these groups are often harder to reach and survey. A better understanding of their specific risk factors is essential to improve the effectiveness and equity of public health interventions.

The Developmental origins of health and disease (DOHaD) paradigm reinforces the importance of targeting the first 1,000 days — from pregnancy to two years of age — as a critical window for promoting healthy behaviours. Yet universal health education programs have shown limited impact among disadvantaged populations, and early interventions specifically tailored to socially vulnerable families remain insufficient. To enhance equity, such interventions must go beyond information provision and incorporate structural levers, which are essential to enabling sustainable behaviour change.

In a context of rising poverty and food insecurity, the EQUI-START project is structured around two complementary objectives to be implemented over three years, beginning in January 2025.

Objectives

The first objective builds on previous analyses conducted in the general population (ELFE cohort), which showed that multiple dimensions of parental socioeconomic position (education, occupation, income) were inversely associated with the risk of overweight at 3.5 years of age. Children of immigrant parents were also found to be at higher risk (Le Gal et al., Scientific Reports, 2024; doi: 10.1038/s41598-023-48431-8), independently of socioeconomic position.

Our aim is to better understand the mechanisms underlying the development of social inequalities in overweight during early childhood. Specifically, we will assess the extent to which children’s energy balance–related behaviours during the first two years of life, combined into lifestyle patterns, explain the inverse social gradient in overweight observed from age 3.5 onward, while examining social determinants in a comprehensive and integrative manner.

Full-time researcher (PhD): Mélissa Baïetto

 The second objective is to complete the ECAIL randomized controlled trial (Lioret et al., BMC Public Health, 2025; doi: 10.1186/s12889-025-25004-0), which evaluates the effectiveness of a childhood obesity prevention program delivered during the first 1,000 days to families experiencing social vulnerability. This program, known as the Malin Program, includes:

  • Personalized nutritional support for families starting during pregnancy, including promotion of breastfeeding; practical advice and guidance for healthier eating; encouragement of more active lifestyles; and reduction of screen exposure;
  • A non-stigmatizing structural component aimed at reducing the cost of quality food, including:
  • From pregnancy onward: baskets of fresh and organic fruits and vegetables sourced through short supply chains; access to over 100 organic grocery products (online); and kitchen utensils and small appliances at reduced prices (online);
  • From the 6 months of age: discount vouchers for foods appropriate for infant and family nutrition, redeemable in all supermarkets.

An in-depth analysis of the intervention processes, at the intersection of epidemiology and the social sciences, will help determine in which contexts, for which populations, and at what level of intensity the intervention is most effective. It will also identify the mechanisms activated by the intervention, as well as the barriers encountered. These findings will strengthen the Malin Program which, since its launch ten years ago, has already supported 250,000 young children and ultimately aims to reach more than 300,000 children and families experiencing social disadvantage in France.

Full-time researchers: Tori Jacobsen, Lucie Vanhoutte, Ketevan Marr, Yannis Sakellaris

Partners: Malin Program (non-profit organization under the French 1901 law), French Red Cross, French Association of Ambulatory Paediatrics (AFPA), French Society of Paediatrics (SFP), Lille University Hospital (CHU de Lille), Valenciennes Hospital Centre (CH de Valenciennes)

 

  Project publications

Poquet D, de Lauzon-Guillain B, Ley D, Charles MA, Sauvegrain P, Lioret S. Intentions, practices, and social representations regarding breastfeeding among women experiencing social disadvantage: findings from the qualitative component of the ECAIL trial. Int Breastfeed J. 2026 Jan 23;21(1):22. doi: 10.1186/s13006-026-00812-1.

Lioret S, Sion O, Hincker P, Béghin L, de Lauzon-Guillain B, Cavalli B, Salinier C, Turck D, Perez N, Subtil D, Brun S, Charlier M, Creps E, Dehon A, Le Gal C, Poquet D, Sauvegrain P, Heude B, Deplanque D, Meyran D, Devouge P, Ley D, Charles MA. Home visiting intervention over pregnancy and the first two years of life to promote healthy feeding practices and energy balance-related behaviors and prevent obesity risk in children from socially disadvantaged families: protocol for a participant-blinded, two-arm, parallel-group randomized controlled trial-the ECAIL study. BMC Public Health. 2025 Oct 29;25(1):3659. doi: 10.1186/s12889-025-25004-0.

 

 Funding for the EQUI-START project: AXA Fund for Human Progress

https://www.youtube.com/watch?v=ek7oLGI3LqM