The risk factors of adverse birth outcomes among immigrant women in the Republic of Korea

Abstract

Background The Republic of Korea (Korea) experienced increases in births from immigrant women steadily over the last 20 years, accounting for a substantial proportion of total births (4.3 %). Nevertheless, little is known about birth outcomes of immigrant women in Korea.

Methods This study compared the birth data of immigrant and native women in Korea and explored factors affecting birth outcomes of immigrant women. A total of 68,074 singletons from immigrant women and 1,644,956 singletons from natives were examined based on the National Birth Registration Database between 2010 and 2013. The outcomes included preterm births, low birth weight and small for gestational age (SGA). Adjusted proportions for the occurrence of preterm births, low birth weight and SGA were calculated, and performed subgroup analysis according to maternal original nationalities, maternal age, parity, and birth region. The birth outcomes of the immigrant group to a vulnerable group in Korea were compared. Add to that, the associated factors with those birth outcomes were assessed in multivariate analyses adjusted for demographic and socioeconomic factors.

Results After adjusted for birth-related factors (infant sex, maternal age, marriage status, and parity) the adjusted proportions for preterm birth (4.9% vs. 4.6%, p < 0.001), low birth weight (4.2% vs. 3.6%, p < 0.001) and SGA (5.7% vs. 7.2%, p < 0.001) were significantly higher for immigrants than natives. However, after additionally adjusted for socioeconomic factors (birth region, parental education level, and occupation), preterm birth and low birth weight were significantly more favorable but SGA were still unfavorable in the immigrant group. The results were similar in the subgroup analysis for immigrants from Southeast Asia, but immigrants from China, Europe, or America revealed similar or more favorable outcomes compared to the native group. The results of stratified analyses showed that primiparous immigrant women and those between the ages of 20-34 had significantly higher proportions of adverse birth outcomes relative to native women. The results that compared to less educated parents or unemployed fathers in the native group revealed that the immigrant group had lower proportion of preterm birth and comparable proportion of low birth weight. Multivariate analysis showed that infant sex, parental ages and economic level of maternal original countries were related to preterm birth and low birth weight. After adjustment with all demographic and socioeconomic factors, the risks of preterm birth and low birth weight was lower, and that of SGA was higher in the immigrant group compared to the native group.

Conclusions This study has provided evidence regarding the disparities in the risks of adverse birth outcomes among immigrant women and native women in Korea. However, to accurate assess the precise status of birth outcomes, and to identify the causes of adverse birth outcomes, additional information (e.g., health status of mothers and infants, monthly income, durations of residency in Korea) is needed. These data will be necessary to develop comprehensive policies that can reduce health disparities and support the successful settlement of immigrants in Korea.