Introduction: Despite changes in prenatal diagnostic methods and perceptions regarding the prognosis of and treatment options for patients with trisomy 18 syndrome, data on the secular changes in patient survival are limited. This study aimed to investigate the survival pattern for such patients. Methods: To investigate the general patient survival patterns, we used data from the vital statistics database of deaths in Japan from 1975 to 2016. We described demographic factors, such as sex, gestational age at delivery, and surgical history, for patients whose primary cause of death was trisomy 18 syndrome. Results: The proportions of deaths within 24 h of birth (4.0% in 1975–1980 to 21.9% in 2011–2016) and at age ≥1 year (8.9% in 1975–1980 to 17.7% in 2011–2016) increased. The median survival time was higher for females, infants born after 37 weeks of gestation, and those who received surgical intervention. The median survival time tripled among patients who received surgical intervention (61.5 days in 1995–2005 to 182.5 days in 2006–2016), and the proportion of such patients increased (from 3.8% in 1995 to 24.1% of the entire affected population in 2016). Discussion/Conclusion: In Japan, the median survival time of infants with trisomy 18 increased over time, and the proportion of death within 24 h and at ≥1 year increased. Greater acknowledgement of the possible benefits of surgical intervention likely led to the increased provision of interventions and contributed to the increased survival time.