Background The diagnosis of functional constipation (FC) is based on the Rome criteria. The last edition of the criteria (Rome IV) for infants and toddlers modified the criteria to differentiate toilet‐trained (TT) and non‐toilet‐trained (NTT) children. These changes have not been validated. We aimed to understand the impact of adding toilet training to the diagnostic criteria and to assess the prevalence of FC. Methods Parents of infants and toddlers from six outpatient clinics (four public, two private) located in three geographically dispersed cities in Colombia completed validated questionnaires to diagnose functional gastrointestinal disorders according to Spanish version of Rome IV criteria (QPGS‐IV). Results A total of 1334 children (24.4 months ±15.0) participated: 482 (36%) TT and 852 (64%) NTT. The prevalence of FC was 21.1%. The prevalence increased with age, 0‐1 years 7.7%; 2 years 18.2%; 3 years 23.7%; and 4 years 37.2%. TT vs NTT for FC 41.9% vs 9.3%, respectively (OR 7.06, 95% CI 5.26‐9.47, P < .0001). TT more likely to report ≥ 3 criteria (OR = 2.43, 95% CI 1.41‐4.21, P = .0015). 18.3% of TT had episodes of fecal incontinence that met the frequency required by Rome for FC (≤1 episode/week). However, 87.1% had fecal incontinence less often. 7.4% of them characterized as large quantity. Conclusion We found no changes in the prevalence of FC using the Rome IV criteria vs Rome III. TT children are more likely to have FC. Study suggests that changes in Rome IV criteria were potentially clinically relevant and to have adequate face validity. Future studies should confirm our findings. The diagnosis of functional constipation (FC) is based on the Rome criteria. The last edition of the criteria (Rome IV) for infants and toddlers modified the criteria to differentiate toilet‐trained (TT) and non‐toilet‐trained (NTT) children. We aimed to understand the impact of adding toilet training to the diagnostic criteria and to assess the prevalence of FC. We found that TT children are more likely to have FC, and there were no changes in the prevalence of FC using the Rome IV criteria vs Rome III.