Objective: To analyze the variations of head circumference (HC) in preterm infants, born with less than 34 weeks of gestation, exposed to histologic chorioamnionitis (CAH), and observed until 2 years of corrected age. Materials and methods: This is a cohort study derived from two prospective studies. The analyzed data corresponded to HC measures obtained from the subjects at three points: birth, 40 weeks, and 2 years of corrected age. The subjects were classified in two groups: exposed and not exposed to CAH. Preterm infants with CAH were divided according to its subtype in chorioamnionitis, subchorionitis and chorioamnionitis plus funisitis. Results: Out of 91 preterm infants included in the study. 41.8% (38/91) presented CAH. At birth, the average measure of HC in exposed infants was 27.7 cm (31,2 percentile), while in not exposed infants it was 28.3 cm. (42,1 percentile). At 40 w...