Background: Placental pathology such as acute chorioamnionitis (ACA) has been implicated in the pathogenesis of diseases in premature infants. This study aims to determine whether there is a relationship between the presence of histological chronic chorioamnionitis (CCA) as known as maternal anti-fetal rejection and the morbidities of very low birth weight (VLBW) infants. Methods: Retrospective analysis included VLBW infants admitted to neonatal intensive care unit in Asan Medical Center from January 2013 to December 2016. Placental examinations were carried out routinely during the study period and were grouped into 4 categories, ACA, CCA, maternal vascular underperfusion and fetal vascular thrombo-occlusive disease. Among them data on the CCA were analyzed using logistic regression for the infants’ morbidities with other clinical characteristics. Results: A total of 406 infants with the mean (±SD) gestational age of 28.5 (±2.8) weeks and birth weight of 1027.2 (±304.4) g were included. The incidences of bronchopulmonary dysplasia, intraventricular hemorrhage grade ≥III, necrotizing enterocolitis stage ≥II, and retinopathy of prematurity (ROP) stage ≥II were 23.3%, 7.8%, 5.2%, and 14.0%, respectively. CCA was revealed in 108 (26.6%), among them 17.6% (19/108) developed ROP, and 16.7% (18/108) underwent treatment of laser photocoagulation. Lower gestational age, lower birth weight, and longer duration of oxygen supply, and the CCA were related development of ROP. After adjustment for gestational age, birth weight, sex and duration of oxygen supply, CCA was related to laser photocoaulation for ROP (adjusted odds ratio 2.0; 95% confidence interval 1.05-3.80, p =0.003). CCA was not associated with other infants’ morbidities. Conclusions: The CCA was an independent risk factor for severe ROP requiring treatment of laser photocoagulation in VLBW infants. Further research about pathogenesis between the anti-fetal rejection thourgh anti-angiogenic effect of CCA and the deregulated angiogenesis of ROP is needed.