Preterm birth, which is defined as birth completed before the 37th week of gestation, is the leading cause of infant mortality and morbidity. Premature birth is usually divided into spontaneous preterm birth (SPP) and medically indicated preterm birth. Risk factors that lead to premature birth are divided into three groups: maternal, fetal and placental risk factors. According to some studies, approximately 30% of all preterm births are thought to have none of the risk factors for preterm birth. This retrospective study was conducted for a five-year period from January 1st, 2019 to December 31st, 2023, at the Clinic for Women's Diseases and Childbirth at KBC Split, with the aim of determining the frequency of premature births and determining the main risk factors that led to premature birth. In the mentioned period, there were a total of 20,773 births, of which 1,248 were completed before the 37th week of gestation. The proportion of premature births was 6% in KBC Split in the mentioned period. Out of 1248 births, 225 (18.03%) were multiple pregnancies, which are also the most common risk factor for premature birth in our study. After them, the second most frequent risk factor was collectively preeclampsia, hypertension and/or HELLP syndrome with a share of 10.74%. They are followed by gestational diabetes mellitus (GDM) with a frequency of 8.17% and maternal infections with a share of 6.89%. Of the fetal risk factors, in addition to multiple pregnancies, intrauterine growth retardation (IUGR) should be singled out with a frequency of 2.16%, and oligohydramnios and polyhydramnios with shares of 2.48% and 1.61%, respectively. Of the placental risk factors, placental abruption with a share of 3.53% and placenta praevia with a share of 2.96% stand out.