출산 연령에 따른 출생아의 출생 결과; 1997-98, 2014-15년 출생통계를 중심으로

Abstract

Objectives: To compare the secular trend of preterm birth (PTB) rate, low birth weight (LBW) rate and multiple birth rate by maternal age at birth. Methods: We used 1997-98 (1,872,720 births) and 2014-15 (1,280,348 births) birth certificate data of Korea excluding extra-marital birth cases. Odds ratio (OR) and 95% confidence intervals were calculated from logistic regression analyses to investigate the secular trend (1997-98 and 2014-15) of maternal age specific PTB rate, LBW rate and multiple birth rate (ie three indicators) adjusted by socio-demographic variables. Results: Between 1997-98 and 2014-15, the birth rate of women aged 25-29 years decreased from 54.8 percent to 22.0 percent. The rate of maternal age at birth increased 2.2 times in aged 30-34 years, 3.9 times in aged 35-39 years, and 4.3 times in aged 40-44 years. The mean age at birth increased from 27.9±3.8 years to 31.7±4.1, mean gestational age decreased from 39.4±1.4 weeks to 38.6±1.6 weeks, and mean birth weight was 3.27±0.45kg and 3.21±0.46kg, respectively. The rate of three indicators during the period increased from 3.3 percent to 6.7 percent in PTB rate, from 3.3 percent to 5.6 percent in LBW rate, and from 1.4 percent to 3.6 in multiple birth rate. After adjustment by socio-demographic variables, the odds ratio of three indicators in birth year of 2014-15 were 2.21 (95% confidence interval: 2.16-2.26) for multiple birth, 1.73 (1.70-1.75) for PTB, and 1.36 (1.34-1.38) for LBW, compared with 1997-98. If maternal age distribution in 2014-15 was similar to that in 1997-98, the rates of three indicators would be 11.9 percent lower in preterm birth (5.9% compared with 6.7%), 12.5 percent lower in low birth weight (4.9% vs. 5.6%), and 25.0 percent in multiple birth (2.7% vs. 3.6%). During the period, the ratio of fluctuation (maximum rate/minimum rate) in three indicators decreased from 2.7 to 1.8 in PTB and from 2.2 to 1.7 in LBW, and increased from 2.3 to 5.5 in multiple birth. Between 1997-98 and 2014-15, the highest increment of three indicators by maternal age was women aged 20-24 years for PTB (OR: 2.06), aged 20-24 years for LBW (1.56), and women aged 30-34 years for multiple birth (2.44). The lower increment of three indicators was observed in terms of maternal age at 35 years and older. Conclusions: Advanced maternal age in women was associated with the risk factors for an adverse child's birth outcomes (PTB, LBW and multiple birth). The risk of increment of PTB and LBW during the period was higher in women age 20-29 years than that of aged 35 years and older. Well designed intervention programme on prenatal care available and accessible to all aged women, and is the ways to reduce adverse child's birth outcomes.