Research for the relationship between threshold of viability and fetal lung structure, and mechanism of fetal hypoplastic lungs

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In Japan as well as western countries, the survival rate of extremely premature infants (ELBW) and very premature infants (VLBW) improved in the 1990s with the spread of new treatment methods such as surfactant therapy, new methods of mechanical ventilation represented by high frequency oscillatory ventilation (HFO), and prenatal steroid therapy. The Committee on Newborn Infants, Japan Society of Pediatrics has performed nation-wide surveys on the outcomes of ELBW and VLBW for reports on the current status of NICU and neonatal mortality in Japan at 5-year intervals. The mortality rate of infants weighing less than 1,000 g at birth significantly declined in the previous two decades from 55.3% in 1980 and 28.2% in 1990 to 17.8% in 2000. In view of this, the Ministry of Health, Labour and Welfare of the Japanese government changed the definition of the threshold of viability in the Maternal Protection Law from 24 weeks of gestation to 22 weeks of gestation in January, 1991. After this change, neonatologists in Japan have increasingly intervened in deliveries at 22-23 weeks' of gestation. To date, 15years have passed since intensive care for infants born at 22weeks' gestation was undertaken and efforts to improve the prognosis of such infants are continuing in Japan. The purpose of this project was as follows :1.For test to validate 22 weeks gestation as threshold of viability1)the analysis lung maturation of fetuses aborted at 21 weeks gestation2)nation wide survey of short term prognosis born at 22-23 weeks gestation3)nation wide survey of short term outcome of infants born weighing less than 500 grams4)the analysis of urine steroid profile of preterm and term infants2.experimental analysis1)the relationship between intrauterine infection and KL-6 production in vitro2)intaratracheal administration of lactoferrin to prevent pseudomonas pneumonia