Secular Trends of Preterm Birth Rate in Primiparous Women by Matermal Age: 1997~1999, 2011~2013 Singleton Birth Certificated Data of Korea

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doi:2015.19.2.296

J Korean Soc Matern Child Health > Volume 19(2); 2015 > Article

Journal of The Korean Society of Maternal and Child Health 2015;19(2):296-303.
DOI: https://doi.org/10.21896/jksmch.2015.19.2.296 Published online July 31, 2015.

Secular Trends of Preterm Birth Rate in Primiparous Women by Matermal Age: 1997~1999, 2011~2013 Singleton Birth Certificated Data of Korea

박상화¹, 임달오²

¹서울대학교 의학연구원 인구의학연구소
²국립공주대학교 보건행정학과

우리나라 초산부의 출산 연령에 따른 단태아 조기분만율추이에 관한 연구, 1997~1999, 2011~2013

박상화¹, 임달오²

¹서울대학교 의학연구원 인구의학연구소
²국립공주대학교 보건행정학과

Abstract

Purpose
The objective of the study was to compare the secular trend of age specific preterm birth (PTB) rate by analyzing singleton birth certificated data among primiparous women (1997~ 1999: 918,115 births, 2011~2013: 690,120 births) of Korea Statistics.
Methods
Odds ratio and 95% confidence intervals were calculated from logistic regression analyses to describe the secular trend (1997~1999 and 2011~2013) of maternal age specific PTB rate (20~24, 25~29, 30~34, 35~39, ≥40) adjusted for infantile sex, maternal education & occupation, and marital status.
Results
The incidence of PTB increased 2.9 percent in 1997~1999 (phase I) to 4.4 percent in 2011~2013 (phase II). Age standardized PTB rate rose from 3.2 percent to 4.2 percent during the period. Compared with age specific PTB rates of phase I, the odds ratio of PTB in birth year of phase II were 1.636 (95% confidence interval: 1.550~1.726) in aged 20~24 years, 1.451 (1.410~ 1.494) in 25~29 years, 1.193 (1.149~1.238) in 30~34 years, 1.068 (0.996~1.146) in 35~39 years and 1.096 (0.939~1.280) in 40 years and older. Compared with PTB rate of women aged 25~29 years in phase I and phase II, respectively, a slightly decrease in adjusted odds ratios among women aged 30~34 was found for PTB rate (1.542 versus 1.171), for women aged 35~39 (2.230 versus 1.567) and for women aged 40 years and older (2.731 versus 1.923).
Conclusions
Rate of PTB between phase I & II increased higher in primiprous women aged 20~ 29 years, whereas rates remained stable in women aged 35~39, and 40 years and older. There was a need to understand the contributing maternal age factors to PTB, and to reduce PTB rate for women aged 20~29 years.

Key Words: preterm, maternal age, primiparous women