The objective of the study was to assess if small- and large-for gestational age term infants have greater health care utilization during the first year of life. The sample included 28,215 singleton term infants (37-42 weeks) without major birth defects delivered from 1998 through 2007 and continuously enrolled at Kaiser Permanente Northwest for 12 months after delivery. Birth weight for gestational age was categorized into 3 levels: <10th percentile (SGA), 10-90th percentile (AGA), >90th percentile (LGA). Length of delivery hospitalization, re-hospitalizations and sick/emergency room visits were obtained from electronic records. Logistic regression models estimated associations between birth weight category and re-hospitalization. Generalized linear models estimated adjusted mean number of sick/emergency visits. Among term infants, 6.2 % were SGA and 13.9 % were LGA. Of infants born by cesarean section, SGA infants had 2.7 higher odds [95 % 1.9, 3.8] than AGA infants of staying ≥5 nights during the delivery hospitalization; of those born vaginally, SGA infants had 1.5 higher adjusted odds [95 % 1.1, 2.1] of staying ≥4 nights. LGA compared to AGA infants had higher odds of re-hospitalization within 2 weeks of delivery [OR 1.25, 95 % CI 0.99, 1.58] and of a length of stay ≥4 days during that hospitalization [OR 2.6, 95 % CI 1.3, 5.0]. The adjusted mean number of sick/emergency room visits was slightly higher in SGA (7.8) than AGA (7.5) infants (P < .05). Term infants born SGA or LGA had greater health care utilization than their counterparts, although the increase in utilization beyond the initial delivery hospitalization was small.