Korean J Obstet Gynecol.  2006 Sep;49(9):1855-1865.

Analysis of Preterm Birth Rate based on Birth Certificate Data: from 1995 to 2003

• Koo YH
• Kim SK
• Shim JY
• Won HS
• Lee PR
• Kim A

Abstract

OBJECTIVE
This study was performed to evaluate changes in the preterm birth rate and risk factors of preterm birth in Korea.
METHODS
A total number of 5,433,746 birth cases from the birth certificate data from 1995 to 2003 obtained from the National Statistical Office of Korea was reviewed and analyzed. We evaluated the annual preterm birth rate for 9 years, seasonal and regional variations, multiple birth rate, the preterm birth rate for women aged 35 years or older. The logistic regression analysis was used to examine the relationship between preterm birth and risk factors including maternal and paternal age, parity, infantile sex, season and region of birth.
RESULTS
The preterm birth rate has increased from 4.25% in 1995 to 10.03% in 2003. Seasonal and regional variations were found. The preterm birth rate was 6.65% in spring, 7.75% in summer, 7.36 in autumn, and 7.38% in winter. The preterm birth rate was 5.06% in Jeollabuk-do, the lowest rate, and 9.17% in Ulsan, the highest rate in Korea. The multiple birth rate has increased from 1.32% in 1995 to 2.01% in 2003. The mean age at first birth was 26 years in 1995, 28 years in 2003, and first birth rate for women aged 35 years or older has increased from 2.4% in 1995 to 4.8% in 2003. The preterm birth rate for women aged 35 years or older also increased from 8.14% in 1995 to 14.74% in 2003. The risk for preterm birth was significantly higher in the women aged 35 years or older, compared with those under 35 years (OR: 1.572, p<0.001). The risk for preterm birth in father aged 40-70 years was higher than those under 30 years (OR: 1.316, p<0.001). In the order of birth, the risk was higher in second or more-born than first-born (OR: 1.122, p<0.001). The odds ratio of preterm birth by infantile sex was 0.84 in male (p<0.001). Risk was significantly higher in multiple birth than in singleton (OR: 20.078, p<0.001).
CONCLUSION
Based on the birth certificate data from 1995 to 2003, the preterm birth rate in Korea has increased since 1995. Older maternal and paternal old age, multiparity, male infant, and multiple birth can be considered as risk factors for preterm birth.

Keyword

Preterm birth; Rate; Risk factors

MeSH Terms

Birth Certificates*
Birth Order
Fathers
Female
Humans
Infant
Jeollabuk-do
Korea
Logistic Models
Male
Multiple Birth Offspring
Odds Ratio
Parity
Parturition*
Paternal Age
Premature Birth*
Risk Factors
Seasons
Ulsan