Contribution of Maternal Age Distribution to Incidence of Preterm Birth; 1997~99 and 2012~14 Singleton Birth Certificated Data of Korea.
- Author:
Sang Hwa PARK
1
;
Hoon KIM
;
Dar Oh LIM
Author Information
1. Institute of Reproductive Medicine and Population, Medical Research Center, Korea.
- Publication Type:Original Article
- Keywords:
singleton preterm birth;
maternal age;
contribution of preterm
- MeSH:
Female;
Humans;
Incidence*;
Korea*;
Logistic Models;
Maternal Age*;
Multiple Birth Offspring;
Odds Ratio;
Parity;
Parturition*;
Premature Birth*
- From:Journal of the Korean Society of Maternal and Child Health
2016;20(3):221-227
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
PURPOSE: The objective of the study was to compare contribution of maternal age to preterm birth (PTB) rates between 1997~99 and 2012~14. METHODS: We used 1997~99 (1,872,720 births) and 2012~14 (1,280,348 births) singleton birth certificated data of Korea Statistics excluding multiple birth and extra-marital birth cases. We decomposed the contributions of age-specific PTB rates and maternal age distribution (Kitagawa's decomposition method) to overall PTB rates during the period. Odds ratio (OR) and 95% confidence intervals were calculated from logistic regression to describe the secular trend of PTB rate by birth year and maternal age. RESULTS: The incidence of PTB increased 1.5 times, from 3.0 percent to 4.6 percent, during 1997~2014. After adjustment by logistic regression for infantile sex, parity and maternal age, the odds ratio of PTB in birth year of 2012~14 was 1.38 (95% confidence interval: 1.36~1.39), compared with incidence of PTB in 1997~99. During the period, PTB rates increased 1.79 times in women aged 20~24 years and 25~29 years (OR: 1.56), whereas rates remained stable in women aged 35 years and older (OR: range from 1.08 to 1.13). 87.5% of the overall increase in the PTB rates was attributable to the increase in the proportion of women aged 30~34 years, but these age group accounted for only a small portion of the increase in PTB rates (OR: 1.27). CONCLUSION: The remainder of the total increment in the PTB rates during the period was explained by increase the proportion of women aged 30~34 years. There was a need to close attention in this area to understand the contributing factors to the secular trend of PTB rates.
