Objective: To investigate differences by gestational age in emergency department visits and re-hospitalizations during the three years following childbirth discharge. Methods: We performed a historical cohort study in Lazio Region, Italy, for infants born in 2007-2008 to resident mothers. Health administrative data were used. Analysis was performed by multinomial logistic regression. Results: Of 90,545 infants, more than 50% had at least one emergency department visit, and 18.8% at least one re-hospitalization. Relative risk ratios of both events increased by decreasing gestational age, and were higher for mothers ≤35 years of age, with low education and of Italian nationality. Residency outside the metropolitan area was associated with an increased risk of re-hospitalization and a decreased risk of emergency department visits. Conclusion: During the three years following childbirth discharge, re-hospitalizations and, to a lesser extent, emergency department use are inversely related to gestational age at birth; socio-demographic factors have an effect on the risk of infant use of hospital resources independent of gestational age.