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OBJECTIVE: To provide instructive information on death and neurodevelopmental outcomes of infants born at 22 and 23 weeks’ gestational age. METHODS: The study cohort consisted of 1057 infants born at 22 to 25 weeks in the Neonatal Research Network, Japan. Neurodevelopmental impairment (NDI) at 36 to 42 months’ chronological age was defined as any of the following: cerebral palsy, hearing impairment, visual impairment, and a developmental quotient RESULTS: Numbers and incidences (%) of infants with death or NDI were 60 (80%) at 22 weeks and 156 (64%) at 23 weeks. In logistic regression analysis, gestational ages of 22 weeks (odds ratio [OR]: 5.40; 95% confidence interval [CI]: 2.48–11.76) and 23 weeks (OR: 2.14; 95% CI: 1.38–3.32) were associated with increased risk of death or NDI compared with 24 weeks, but a gestational age of 25 weeks (OR: 0.65; 95% CI: 0.45–0.95) was associated with decreased risk of death or NDI. In the systematic review, the medians (range) of the incidence of death or NDI in 8 cohorts were 99% (90%–100%) at 22 weeks and 98% (67%–100%) at 23 weeks. CONCLUSIONS: Infants born at 22 and 23 weeks’ gestation were at higher risk of death or NDI than infants at born at 24 weeks. However, outcomes were improved compared with those in previous studies. There is a need for additional discussions on interventions for infants born at 22 or 23 weeks’ gestation.

OBJECTIVE:To compare neonatal outcomes of very low birth weight (VLBW) infants admitted to NICUs participating in the Canadian Neonatal Network and the Neonatal Research Network of Japan.METHODS:Secondary analyses of VLBW infants in both national databases between 2006 and 2008 were conducted. The primary outcome was a composite of mortality or any major morbidity defined as severe neurologic injury, bronchopulmonary dysplasia, necrotizing enterocolitis, or severe retinopathy of prematurity at discharge. Secondary outcomes included individual components of primary outcome and late-onset sepsis. Logistic regression adjusting for confounders was performed.RESULTS:A total of 5341 infants from the Canadian Neonatal Network and 9812 infants from the Neonatal Research Network of Japan were compared. There were higher rates of maternal hypertension, diabetes mellitus, outborn, prenatal steroid use, and multiples in Canada, whereas cesarean deliveries were higher in Japan. Composite primary outcome was better in Japan in comparison with Canada (adjusted odds ratio [AOR] 0.87, 95% confidence interval [CI] 0.79–0.96). The odds of mortality (AOR 0.40, 95% CI 0.34–0.47), severe neurologic injury (AOR 0.57, 95% CI 0.49–0.66), necrotizing enterocolitis (AOR 0.23, 95% CI 0.19–0.29), and late-onset sepsis (AOR 0.22, 95% CI 0.19–0.25) were lower in Japan; however, the odds of bronchopulmonary dysplasia (AOR 1.24, 95% CI 1.10–1.42) and severe retinopathy of prematurity (AOR 1.98, 95%CI 1.69–2.33) were higher in Japan.CONCLUSIONS:Composite outcome of mortality or major morbidity was significantly lower in Japan than Canada for VLBW infants. However, there were significant differences in various individual outcomes identifying areas for improvement for both networks.

OBJECTIVE. Our goal was to investigate the neonatal mortality rate and the mortality rate during the NICU stay for extremely low birth weight infants born in Japan in 2005. METHODS. The Committee of Neonatal Medicine of the Japan Pediatric Society retrospectively surveyed the deaths of extremely low birth weight infants born and hospitalized between January 1 and December 31, 2005. From 297 institutions in Japan, data on 3065 extremely low birth weight infants, which represented 98.4% of those reported in the maternal and health statistics of Japan in 2005, were collected. RESULTS. The neonatal mortality rate and the mortality rate during the NICU stay were 13.0% and 17.0%, respectively, which were lower than 17.7% and 21.5% in the survey in 2000. The neonatal mortality rates and the mortality rates during the NICU stay were 53.3% and 67.7% in the CONCLUSION. The mortality rates of extremely low birth weight infants who were born in 2005 demonstrated definite improvement.

OBJECTIVES. The objectives of this study were to describe the characteristics and morbidity of very low birth weight infants, to identify the medical intervention for these infants, and to evaluate the factors affecting the mortality of these infants among the participating hospitals.METHODS. A large multicenter neonatal research network that included level III NICUs from throughout Japan was established. A standardized mortality rate was formulated by giving a ratio of the observed deaths and the predicted deaths based on a 100-g birth weight interval mortality. A regression model was used to predict the factors that affect neonatal mortality.RESULTS. The network included 37 centers and 2145 infants weighing ≤1500 g, born or admitted to the centers in 2003. Gestational age and birth weight of studied infants were 28.6 ± 3.6 gestational weeks (mean ± SD) and 1025 ± 302 g, respectively. Overall, 11% of the infants died before being discharged from hospitals (range: 0%–21%). The standardized mortality rate varied among the facilities (range: 0%–30%). No association between the annual number of patients admitted and standardized mortality rate was found. Among all of the very low birth weight infants, 14% were outborn infants, 72% were delivered by cesarean sections, 27% had patent ductus arteriosus, 3% had gastrointestinal perforation, 8% had bacterial sepsis, and 13% had intraventricular hemorrhage. Medical interventions involved were: 41% antenatal corticosteroids, 54% surfactant therapy, 18% postnatal steroids for chronic lung disease, and 29% high-frequency oscillatory ventilation. We found variations in the medical interventions and the clinical outcomes among the centers.CONCLUSIONS. The overall survival rate for very low birth weight infants among neonatal centers in Japan was ∼90%. However, differences in the morbidity and mortality were observed among these centers.

Objective. Evaluation of the placenta provides some important insights into pathophysiologic changes that take place during the prenatal and intrapartum process. We investigated the relationship between placental findings and periventricular leukomalacia (PVL) to obtain a better understanding of its cause.Methods. Thirty-two preterm infants with PVL delivered before 34 weeks’ gestation, between 1990 and 1999, were classified into 4 groups according to the onset of brain injury assumed from ultrasonographic presentation and clinical course: 2 Antenatal, 22 Peripartum, 5 Postnatal, and 3 in an unknown time of onset group. We evaluated the gross and histopathologic features of the placentas of each group and compared them with those of a control group matched by birth weight and gestational age in terms of the frequency of major placental findings. Potential confounding factors were controlled in logistic regression analyses.Results. Gross lesions with disturbance of uteroplacental circulation, including massive retroplacental hematoma, extensive infarction or thrombosis, and marked basal or perivillous fibrin deposition, were observed more frequently in the Antenatal + Peripartum combined subgroup than in the controls (41.7% vs 13.7%). Placentas from the Antenatal + Peripartum subgroup also demonstrated a significantly higher frequency of ischemic changes in villi, based on histopathologic examination, as compared with the control group (54.2% vs 13.7%). These associations remained after adjustment for confounding factors in logistic regression analyses (odds ratio: 4.04, 95% confidence interval: 1.40–11.67; and odds ratio: 7.28, 95% confidence interval: 2.50–21.20; respectively). Frequencies of chorioamnionitis and twin placentation tended to be higher in PVL cases than in the controls, although the differences were not statistically significant (46.9% vs 37.9%, 37.5% vs 20.0%, respectively).Conclusions. These results suggest that disturbed placental circulation underlies the development of PVL in the majority of cases with prenatal and peripartum brain injury. In chorioamnionitis cases, certain additional factors were suggested in the genesis of PVL. Thus, placental examination is essential for elucidating the pathophysiologic changes leading to PVL in the perinatal process.

OBJECTIVE. The aim was to determine whether inhaled nitric oxide therapy improves neurodevelopmental outcomes for infants with preterm persistent pulmonary hypertension of the newborn. METHODS. We conducted a historical cohort study to compare the 3-year incidence of cerebral palsy in preterm singleton infants ( RESULTS. The incidence of cerebral palsy among patients treated with inhaled nitric oxide was 12.5%, whereas that among patients treated with 100% oxygen was 46.7%. After adjustment for maternal fever (≥38°C) during delivery, birth weight, Apgar score at 5 minutes, high-frequency oscillatory ventilation, and surfactant therapy, inhaled nitric oxide therapy, compared with 100% oxygen therapy, was associated with a decreased risk of cerebral palsy in preterm infants with persistent pulmonary hypertension of the newborn. CONCLUSION. Inhaled nitric oxide therapy decreases the risk of cerebral palsy in preterm infants with persistent pulmonary hypertension of the newborn.

Objective. The authors have previously shown the association of elevated neonatal serum IgM and chorioamnionitis in infants in whom pulmonary emphysema characteristic of Wilson-Mikity syndrome subsequently developed. This paper extends the observation to the measurement of polymorphonuclear leukocyte elastase-α1-proteinase inhibitor complex (PMN elastase-α1-PI) in tracheal aspirates of infants with chronic lung disease. Patients. Tracheal aspirates were obtained from 90 very low birth weight neonates within 24 hours of birth. Serum also was collected within 72 hours of birth, and placentas were examined for signs of inflammation. Results. The mean PMN elastase-α1-PI was significantly elevated (21.8 µg/mg albumin) in infants with a pulmonary emphysema syndrome like that designated by Wilson-Mikity compared either with those with bronchopulmonary dysplasia (1.5 µg/mg albumin, P < .01) or those with respiratory distress syndrome in whom bronchopulmonary dysplasia did not develop (2.3 µg/mg albumin, P < .01). Infants with pulmonary emphysema had a significantly elevated mean serum IgM and a high incidence of chorioamnionitis. Conclusions. The level of PMN elastase-α1-PI was increased in the tracheal aspirates of newborns in whom pulmonary emphysema developed. Intrauterine inflammation may increase the level of PMN elastase in the fetal respiratory tract. This increase in PMN elastase-α1-PI in fetal lung tissue may cause lung injury in utero, resulting in postnatal pulmonary emphysema consistent with the Wilson-Mikity syndrome following ventilation.