Newborns, especially preterm infants, have an immature immune system, which, in combination with the required medical interventions necessary for keeping the neonate alive may lead to an increased risk of infection. Even after reaching stability and adapting to the environment, preterm infants have adverse prognoses regarding infections and long-term outcomes compared to their full-term counterparts. The objective of this study was to research differences in the number and severity of infections between preterm and full-term infants during their first year of life. To answer this question, a monocentric prospective study was conducted in a pediatric practice in Vienna, including 71 full-term infants and 72 preterm infants who were observed during their first year of life regarding occurring infections. In respective samples, there was a significantly higher total number of infections in preterm (mean 6.01 ± 3.90) compared to full-term infants (3.85 ± 1.72) during the observation period of one year. Particularly the count of respiratory and severe infections was considerably higher in preterm infants. Otorhinolaryngeal infections were the most frequent of all types of infections in both groups. The pregnancy period, number of siblings, and length of the postnatal hospital stay, were observed as significantly influencing factors which affected the total number of infections. The group of early term infants (37+0 weeks to 38+6) was not significantly different to late term babies (>39+0). The acquired knowledge about the increased risk of infections should lead to a more extensive care for preterm infants, with the objective of reducing the rates of complications, morbidity and mortality in this vulnerable age group in the future.