Changes of Maternal Age Distribution in Live Births and Incidence of Low Birth Weight Infants in Advanced Maternal Age Group in Korea

Moon, Joo Young; Hahn, Won Ho; Shim, Kye Shik; Chang, Ji Young; Bae, Chong Woo

Abstract

PURPOSE
The aim of our study is to identify the demographic changes of maternal age distribution in live births and incidence of low birth weight infants in advanced maternal age (> or =35 years of age) group at the time of birth in Korea.
METHODS
Birth statistics in 1995, 2000, 2005, and 2008 were collected from Korean Statistical Information Service. Based on the data, total births in each group were 715,000, 634,000, 435,000, and 465,000, respectively. Maternal age distribution ranged from the age of 15 to 50, which were all fertile women. Infants were divided into groups according to birth weight. After maternal age distribution of each year and proportion of advanced maternal age group were examined, a retrospective analysis was conducted on incidence of low birth weight infant (LBWI) in advanced age pregnancy.
RESULTS
Number of live births was constantly decreasing during the period of investigation. There was a shift in maternal age distribution; fertile women of the age of 25 to 29 accounted for 54.2% and 51.7% in 1995 and 2000 respectively, whereas those of the age 30 to 34 accounted for 40.8% and 42.7% in 2005 and 2008, respectively. Rate of delivery in elderly gravida were 4.8%, 6.9%, 10.8%, 14.5% in 1995, 2000, 2005 and 2008 respectively, showing a rapid increase. Of the live births, LBWI accounted for 3.0%, 3.8%, 4.3%, 4.9%, thus being increased by about 1.5 times. Overall, with rates of 7.8%, 10.3%, 15.2%, 19.0%, respectively, the proportion of advanced maternal age group with resultant LBWI was higher than that of elderly gravida alone.
CONCLUSION
While there has been a constant decrease in number of live births in the last decade in Korea, proportion of advanced maternal age group is rapidly increasing and incidence of LBWI is also gradually increasing. Furthermore, considering that the incidence of LBWI among elderly gravida was increased by a higher degree than proportion of elderly gravida in maternal age distribution, maternal age can be one of the factors causing LBWI.