Birth outcomes of immigrant women married to native men in the Republic of Korea: a population register-based study

OBJECTIVES The Republic of Korea (Korea) has experienced a steady increase in the number of births from immigrant women over the last 20 years. However, little is known about the birth outcomes of immigrant women in Korea. This study compared Korean birth data from immigrant and native women who married native men, and explored the factors that affected birth outcomes among immigrant women. DESIGN Observational cross-sectional study. SETTING Nationwide registry-based study in Korea. PARTICIPANTS A total of 70 258 records from immigrant women and 1700 976 records from native women were examined using the National Birth Registration Database, from 2010 to 2013. INDEPENDENT VARIABLE Native Korean women and immigrant women who married native men. OUTCOMES Proportion of preterm births, post-term births, low birth weights and macrosomia. RESULTS Adjusted ORs (aOR) were calculated for the adverse birth outcomes, and subgroup analyses were performed according to parity and mothers from three Asian countries (China, Vietnam, the Philippines). Multivariate logistic regression analyses were also conducted to evaluate the association of these factors with birth outcomes among immigrant women. Immigrant women had higher OR of post-term births (aOR 1.62; 95% CI 1.44 to 1.83) and low birth weights (aOR 1.17; CI 1.12 to 1.22). Mothers from the Philippines had higher OR of preterm births (aOR 1.26; CI 1.12 to 1.52) and Chinese mothers had higher OR of macrosomia (aOR 1.55; CI 1.44 to 1.66). The OR of post-term births and low birth weights was significantly higher in the first pregnancies of immigrant women. CONCLUSIONS This study has demonstrated higher proportions of adverse birth outcomes among immigrant women who married Korean men, compared with native women in Korea. Policies reducing the gap in birth outcomes between native and immigrant women are needed.