Characteristics of Infants Born at 36 Weeks of Gestation: A Chart Review of All Infants Born in a Single Year

Background: In Japan, the total number of births is decreasing, while the proportions of late preterm and early term infants are increasing. Infants born at 36 weeks of gestation (hereinafter “36-week infants”) are not considered an indication for hospitalization, resulting in limited clinical data and insufficient understanding of their actual conditions. In this study, we aimed to examine the characteristics of 36-week infants. Methods: We reviewed the medical records of mothers and their 36-week infants born at the Kyorin University Hospital from April 2014 to March 2015. We evaluated birth weight using “standard values for physical measurements at birth according to gestational age.” F-test and Student’s t-test were used to examine the difference in mean gestational age between the 36-week infants who were hospitalized and those who were not hospitalized. Results: We included 84 infants, with multiple births accounting for 63%. Overall, 20% of the infants were born through assisted reproductive technology, 54% required hospitalization, 87% were fed orally rather than through a gastric tube, and 82% received a simple glucose solution for intravenous nutrition. Among the full-term infants, 3.6% weighed below the 10th percentile of the standard weight. Of the 11 children who underwent developmental and intelligence tests, 3 had below-average scores. Conclusions: Infants born at 36 weeks of gestation is an absolute indication for hospitalization. ​Proactive tube feeding may be considered for 36-week infants. Extending follow-up throughout infancy and early childhood is beneficial for 36-week infants.