J Korean Soc Matern Child Health.  2017 Jan;21(1):55-62. 10.21896/jksmch.2017.21.1.55.

The Relationship between Maternal Age at Birth and Intertwin Birth Weight Discordance in Korea

• Park SH
• Lim DO

• KMID: 2449564
• DOI: http://doi.org/10.21896/jksmch.2017.21.1.55

Abstract

PURPOSE
To compare the relationship between intertwin birth weight discordance and maternal age at birth.
METHODS
There were 51,726 pairs of twins born from 2007 to 2014 according to the birth certificate data of Korea Statistics (3,701,806 births). The data were excluded due to extra marital births, home births, and teenage births. Birth weight discordance rate (%) was calculated according to the following formula: (larger birth weight - smaller birth weight)/(birth weight of the larger twin) ×100. The odds ratio of intertwin birth weight discordance rate (≥25%) in maternal age at birth was calculated by logistic regression adjusted by the year of birth, gestational age, maternal education, infantile gender and paternal age.
RESULTS
The mean birth weight of the heavier twin and that of the lighter twin were 2.536 kg and 2.254 kg, respectively. The mean birth weight difference of intertwins was 0.282 kg. The mean birth weight discordance rate by maternal age was 10.5 percent for maternal ages between 20 and 29 years, 11.0 percent for between 30 and 34 years, and 11.4 percent for 35 years and older. The frequency of birth weight discordance level of ≥25 percent increased as the maternal age increased. The rate of birth weight discordance (≥25%) was 7.7 percent for maternal ages between 20 and 29 years, 8.3 percent for between 30 and 34 years, and 8.7 percent in for 35 years and older. Compared with women from 20 to 29 years of age, the odds ratio of ≥25 percent discordance was 1.094 (95% confidence interval: 1.005~1.190) for 30 to 34 years, and 1.164 (1.401~1.301) for 35 years and older. The odds ratio of ≥25 percent discordance for the different-sexed twins was higher than that of the same-sexed twins in overall maternal age groups of 20 to 29 years, 30 to 34 years, and 35 years and older.
CONCLUSION
The risk of birth weight discordance level of ≥25 percent was associated with the older maternal age. More research is required to understand the risk factors of intertwin birth weight discordance for older women.

Keyword

birth weight discordance; maternal age; twin birth

MeSH Terms

Birth Certificates
Birth Weight*
Education
Female
Gestational Age
Humans
Korea*
Logistic Models
Maternal Age*
Odds Ratio
Parturition*
Paternal Age
Risk Factors
Twins