우리나라 월별 출생 빈도의 변동에 관한 연구, 2000-2012 = Monthly Variation of Births in Korea, 2000-2012

다국어 초록 (Multilingual Abstract)

Objectives: The objective of this study was to analyze the monthly variation of birth by year of birth (2000-2012), birth order and marital status. Methods: The analysis was based on birth data of Korea (634,501 births in 2000, 435,301 births in 2005, 470,171 births in 2010 and 484,550 births in 2012). As the percent distribution in monthly number of births appears to be influenced by the different number of day of month, we used the index of birth occurrence (IBO) for analyzing of monthly variation in birth. IBO is defined as a ratio of the average number of births per day of the month to the average number of births per day of the year, with the base set at 100. Results: The monthly distribution of births was bimodal, with a major peak extending from January to March, a minor peak from October to September, and a major trough in December. During the 2000-2012, IBO was highest for January (111), and lowest for December (89). The IBO in first birth order was highest for January (112), and lowest for June (89), and the variations of IBO in first birth order showed wide fluctuation as compared with the IBO of non-first birth order. The monthly pattern of IBO for extramarital births showed lower fluctuation from a peak of 107 to a trough of 92 than for the marital births. The pattern of the IBO for first births, showed a major peak in January-February (wedding in April-May: index of marriage occurrence: 126-127) and a minor peak in October-November (wedding in September-December: 126-143). The monthly distribution of first births appeared to be influenced to some extent by a monthly pattern of marriage. Conclusions: There was a bimodal pattern in birth seasonality: a major peak in January-March, a trough in June-July, a minor peak in October-September, and a trough around December.