Objective: To evaluate the association between having received iron during pregnancy and the size of the child at birth in the Peruvian population. Materials and methods: Descriptive, retrospective and cross-sectional study based on information obtained from the database of the National Institute of Statistics and Informatics (INEI), referring to the demographic and family health survey (ENDES) of the year 2021, which included a two-stage sample, probabilistic, stratified and independent, designed to be nationally representative. The variables considered were whether or not the patient received any iron supplement during pregnancy and the size of the child at birth. For the association analysis, the Pearson Chi-square test was performed using the SPSS statistics 25 software. Results: 51.10% of pregnant women who took iron supplements had children with normal weight, 46.50% of pregnant wo...