This study aims to determine the association of small for gestational age (SGA) and large for gestational age (LGA) at birth with hospital readmission after postpartum discharge for up to 28 days of delivery. This is a population-based, data-linkage study using the French National Uniform Hospital Discharge Database. "Healthy " singleton term infants born between January 1st, 2017, and November 30th, 2018, in the French South region were included. SGA and LGA were defined as birth weight < 10th and > 90th percentiles, respectively, according to sex and gestational age. A multivariable regression analysis was performed. Among 67,359 included infants, 2441 (3.6%) were readmitted, and 61% of them were hospitalized within 14 days postpartum. Hospitalized infants were more likely to be LGA at birth (10.3% vs. 8.6% in non-hospitalized infants, p < 0.01); the proportion of SGA infants did not differ between both groups. Compared to appropriate birth weight for GA (AGA) infants, LGA infants were more often hospitalized for infectious diseases (57.7% vs. 51.3%, p = 0.05). After regression analysis, LGA infants had a 20% higher odds of being hospitalized than those born AGA (aOR (95%CI) = 1.21 (1.06-1.39)), while aOR (95%CI) for SGA was 1.11 (0.96-1.28).Conclusion: In contrast to SGA, LGA was associated with hospital readmission during the first month of life. Follow-up protocols that include LGA should be evaluated.