Factors influencing timing of neonatal discharge in Japan: retrospective study

Background: The aim of this study was to evaluate the birth and discharge dates of neonates and analyze their distribution over days of the week and the old lunar calendar.

Methods: A retrospective study of the neonates discharged in the years 1990, 2000, 2005, and 2010 was conducted in a general hospital in Tokyo, Japan. Data are represented as odds ratios (OR) of the total number of discharges per day divided by the expected number of days per year, for each day of the week as well as each 6 day cycle of the lunar calendar.

Results: The timing of discharge has an uneven distribution across the days of the week, with weekday discharge rates significantly lower than weekend discharge rates. This uneven distribution is particularly significant in the preterm subgroup. In contrast, there is a minor uneven distribution of births across the days of the week and that of discharges across the 6 day cycle of the lunar calendar. Logistic regression analysis for 2005 and 2010 identified admission fee paid by insurance and prematurity as significant factors associated with weekend/holiday discharge (OR, 1.84; 95% confidence interval [CI]: 1.23-2.75; OR, 1.71; 95% CI: 1.15-2.55, respectively). The average length of stay of neonates discharged on the weekend was longer than that for those discharged on a weekday, in both term and preterm infants.

Conclusions: Japanese parents prefer the convenience of weekends over old superstitions about using the lunar calendar to determine the discharge date.