[Live birth distribution by time and place from 1981 to 1998 in Japan].

OBJECTIVES: To investigate the diurnal rhythm of live births labored spontaneously, and the effects of obstetric intervention on birth time distributions. METHODS: The data of live births tabulated by time (one-hour intervals), date and birthplace throughout Japan between 1981 and 1998 were obtained with permission from the former Ministry of Health and Welfare. Together with an investigation of hourly birth numbers by place in each year, an annual transition of hourly birth rates in medical institutions and the diurnal rhythm of birth numbers in maternity homes and at home were analyzed using regression analysis. RESULTS: In every calendar year studied the hourly live birth numbers at hospitals showed a single-peak distribution pattern with maximum values at 13:00-15:00. The annual transition of hourly birth rates showed a 10% (birth numbers base) decrease in the 11:00-13:00 period in 1998 as compared with that in 1981, while there was a corresponding increase of 8% in the 13:00-15:00 period. Hourly birth numbers at clinics showed a double-peak distribution pattern with maximum values during the 11:00-12:00 and 14:00-15:00 periods in early 1980, while a single-peak distribution with a maximum value during the 13:00-15:00 period appeared in 1989 and has remained thereafter. Hourly birth rates (birth numbers base) increased by over 6% in the 13:00-15:00 and 17:00-20:00 periods over the past 18 years, while they decreased by 10% in the 9:00-13:00 period. The results at maternity homes were clearly different from those at hospitals and clinics. The live birth numbers totaled for the 18 years showed a double-phase distribution with a maximum value in the 6:00-7:00 period and a minimum value in the 19:00-20:00 period. The best-fit regression model for the obtained data was a sine curve with a maximum value at 6:00 (coefficient of determination 0.97). Hourly distributions of live births at home also fitted best to a since curve with the maximum value again at 6:00 (coefficient of determination 0.95). CONCLUSIONS: The results suggested that the timing of spontaneous live births follows a circadian rhythm and that obstetric intervention affects time distributions of live births by shifting over 10% of births during the night and early morning to a working day service time (9:00-17:00).

Nationwide description of live Japanese births by day of the week, hour, and location.

To characterize temporal variations of live births in Japan, we analyzed data on the 1,203,147 births of 1998. In hospitals, with 20+ beds, the daily average of live births was significantly lower at weekends and national holidays (mean=1,433, SD = 100) than on weekdays (mean = 1,957, SD = 126). Hourly distributions of live births showed a single sharp peak at 1:00-2:59 pm on weekdays with a small peak at an earlier hour on Saturdays, Sundays and national holidays. The results in clinics, with no bed or less than 20 beds, were similar to those in hospitals except on Saturdays. The difference in the daily average of live births between Saturdays and weekdays was smaller in clinics than that found in hospitals, and hourly distributions on Saturdays resembled those of weekdays but not Sundays or national holidays. Maternity homes showed no differences in the mean number of daily live births over the days of the week including national holidays, and no clear peak of percentage distributions of hourly live births on each day of the week. The present study suggests that the weekly and hourly variations observed in hospitals and clinics are not due to a biological rhythm of labor, but to obstetric intervention in the timing of delivery, either through induction of labor or elective cesarean section.

[Effects of nutrition education for residents on intake of lipid-related nutrients].

OBJECTIVES: Health education for residents is now common, but only a few studies of its effects have been made. The purpose of this study was to investigate the effects of nutrition education for residents on intake of lipid-related nutrients. METHODS: A total of 79 females (40-64 years) who underwent a health examination for residents in a town, Nara Prefecture and were found to have total serum cholesterol levels between 220 mg/dl and 300 mg/dl were divided into two groups. In the first group, nutrition education was performed during the first 24 weeks and no education was performed during the second 24 weeks as the self-control period. In the second group, no education was given during the first 24 weeks as the waiting period but was performed during the second 24 weeks. During the education period, dietary intervention for individual subjects was performed 3 times at intervals of 8 weeks by trained dietitians. The intake of nutrients was estimated by the food frequency questionnaire developed by Ueshima and Okayama, and changes in the intake of nutrients adjusted for total energy were used for evaluation of the effects of the education. RESULTS: In the first group of 42 subjects, three discontinued during the education period and two during the self-control period, and in the second group of the 37 subjects, six discontinued during the waiting period and three during the education period. At the end of the education period, for the total of 67 subjects (39 and 28 in the first and second groups, respectively), the total energy adjusted intake of lipid, cholesterol and saturated fatty acid were significantly lower and the PS ratio was significantly higher than in the second group during the waiting period. During the self-control period after the education, the adjusted intake of lipid-related nutrients remained unchanged in the 37 subjects of the first group who had been given the nutrition education in the first 24 weeks, and it was significantly lower at the end of the 48-week test period than at the baseline examination. The percentage of the subjects showing a desirable intake pattern of major lipid-related nutrients increased significantly after the education period. CONCLUSIONS: These results indicate that the intake of lipid-related nutrients can be decreased by educating individual subjects about nutrition and the effects are maintained for at least 24 weeks.