Objective To investigate levels of lipid soluble vitamins A,D and E in premature infants with early-onset pneumonia and to identify their influencing factors.Methods This study was a single-center case-control study,by selecting 100 premature infants who received treatment in the Neonatal Care Unit of Zhongshan People's Hospital from November,2022 to June,2023 as the study sample.Premature infants were divided into the pneumonia group (n=50)based on whether they developed pneumonia,collectively referred to as the observation group.Premature infants who were treated and discharged from our hospital at the same time and had no special medical history (n=50)were selected,collectively referred to as the control group.We used high-performance liquid chromatography to test the content of lipid soluble vitamins A,D and E in serum samples of two groups of premature infants.We compared the clinical data of two groups of premature infants and pregnant women,as well as indicators,including lipid soluble vitamin A,D and E levels. Logistic regression model was used to identify the influencing factors of premature pneumonia patients.Results The observation group showed significantly higher levels of premature rupture of membranes in pregnant women and children (gender,history of resuscitation,use of respiratory assistance ventilation,birth weight, length of hospitalization)compared to the control group (P<0.05).The early serum lipid soluble vitamin A,D and E levels in the two groups of premature infants showed that the observation group had significantly lower levels of vitamin A and vitamin E compared to the control group (P<0.05).Multivariate logistic regression analysis showed that female premature infants and premature rupture of membranes in pregnant women were risk factors for premature pneumonia (P<0.05),while high serum vitamin A and vitamin E were protective factors for premature pneumonia (P<0.05 ).Conclusion There is a lack of lipid soluble vitamin A and E levels in premature infants with early-onset pneumonia,and the presence of a female premature infant,a history of premature rupture of membranes in the pregnant mother,and a lack of serum lipid soluble vitamin A and E are influencing factors for premature pneumonia.