Trisomy 18 syndrome is a common autosomal aneuploidy chromosomal abnormality caused by the presence of extra chromosome 18 that leads to malformations of various parts of the body. In this study, we retrospectively investigated the effect of the medical progression and prognosis of 44 cases of trisomy 18, admitted to our neonatal intensive care unit between 1992 and 2013. The patients were divided into group A (n=20, 19922002) and group B (n=24, 20032012). Following delivery, karyotype, gender, gestational weeks, birth place, cesarean section, Apgar score and birth weight were analyzed using the Fisher’s exact test, unpaired ttest and MannWhitney U test. Based on the statistical results, a comparison was made of the two groups and no significant differences were observed. Clinical data of major complications, mechanical ventilation, discharge from hospital and survival days were reviewed for the cases of trisomy 18. Of the 44 patients, 42 had cardiac anomaly, 16 had esophageal atresia, and 3 patients had brain anomaly. Ventilation treatment was performed in 29 cases (65.9%) and an increased percentage was identified in group B patients. The percentage survival was estimated using KaplanMeier curves and the two groups were analyzed using the generalized Wilcoxon test. Improvement in life prognosis was observed in group B as compared to group A. The logrank test was used to assess survey periods of 180 days, 1 year, and the entire observation period. Although significant differences were observed for the prognosis of trisomy 18 at 180 days after birth, after 1 year and the entire survey period after birth, the significant differences were not confirmed. In conclusion, results of the present study provide information concerning genetic counseling for parents/guardians and life prognosis, prior to applying intensive management to newborns with trisomy 18.