The clinical management and outcomes of extremely preterm infants in Japan: past, present, and future

There is a wide variation in neonatal mortality rates across regions and countries. Japan has one of the lowest neonatal mortality rates in the world; in particular, the mortality rate of extremely preterm infants (i.e., those born before 26 weeks of gestation) is much lower in Japan than in other developed countries. In addition, Japan has low incidences of intraventricular hemorrhage, necrotizing enterocolitis, and late-onset sepsis, a very high incidence of retinopathy of prematurity, and a relatively high incidence of chronic lung disease. In Japan, general perinatal medical centers (PMCs), which are PMCs that offer the highest levels of care, are required to have an obstetric department with maternal-fetal intensive care units as well as a neonatal or pediatric department with neonatal intensive care units (NICU), in order to promote antenatal rather than neonatal maternal transfer of high-risk cases. The limit of viability of extremely preterm infants is 22 weeks of gestation, and approximately half of them are estimated to receive active resuscitation. The clinical management of extremely preterm infants in Japan are characterized by (I) circulatory management that is guided by neonatologist-performed echocardiography, (II) relatively invasive respiratory management, (III) nutritional management, which entails the promotion of breast milk feeding, early enteral feeding, routine glycerin enema, and the administration of probiotics, (IV) neurological management by means of minimal handling, sedation of ventilated infants, and serial brain ultrasounds, and (V) infection control with the assistance of serial C-reactive protein (CRP) monitoring. Thus, this review provides a brief description of the development of neonatology in Japan, introduces the unique features of Japanese clinical management of extremely preterm infants, and overviews their outcomes.