To study the rate of iron-fortified infant formula (IFF) use in young children in France and its association with socioeconomic factors. The ELFE national birth cohort included, in 2011, 18 329 living births in 349 hospitals randomly selected. The present analyses were restricted to children with follow-up at age two years. Milk consumption was evaluated by parental telephone interview, and its association with socioeconomic factors was studied. The 12 341 analysed children had a mean age of 26 months; 50% were girls. Rate of IFF use before two years old and at two years old was 65% and 43%, respectively. At age two years, use of IFF was lower with young age of the mother (adjusted OR [aOR] = 0.4, 95% CI: 0.3-0.5), low educational level (aOR = 0.7, 95% CI: 0.6-0.9), high parity (aOR = 0.3, 95% CI 0.2-0.4), and mother smoking (aOR = 0.8, 95% CI: 0.7-0.9) as well as low household income (aOR = 0.5, 95% CI: 0.4-0.7), and parents' unemployment (aOR = 0.7, 95% CI: 0.5-0.9). In this national population-based study, the rate of implementation of the ID prevention strategy was much lower at two years old than before two years old, and significantly lower in disadvantaged populations.