Characteristics of pregnant women and their newborns of the Korean CHildren’s ENvironmental health Study (Ko-CHENS)

Abstract

BACKGROUND AND AIM: The Korean CHildren’s ENvironmental health Study (Ko-CHENS) is a nationwide birth cohort study investigating the effects on children’s health and development. As core cohort recruitment was closed in 2020, we disclose the baseline profiles and the characteristics of the participating mothers and children using questionnaires administered during pregnancy and delivery outcomes. METHODS: Thirteen Regional Centers located throughout Korea were responsible for recruiting women in early pregnancy residing in their respective recruitment areas. Self-administered questionnaires and medical records were collected to secure information on demographic factors, socioeconomic status, environmental exposure, lifestyle, and delivery information. In the period up to delivery, we measured indoor environmental exposure and collected bio-specimens, including blood, urine, and umbilical cord blood. RESULTS:The total number of pregnancies was 5,799 and discounting pregnancies by the same woman, the study included 5,581 unique mothers and resulted in 5,452 live births. Response rate of the questionnaires of recruited women was 98.4% and the mean gestational ages (GA) was 14 weeks. The mean age of the subjects was 31.9 years old and the result showed 0.6% of maternal smoking and 1.8% of maternal alcohol drinking during pregnancy rate. Out of 5,581 mothers, we also obtained 5,221 labor and delivery record resulted in 5,213 live births and a sex ratio of births was 49 girls to 51 boys, with 38.6 weeks mean GA at delivery. Preterm delivery rate in singleton pregnancies was 7.8% and showed higher rate with older mothers. The mean weight at birth for total newborn was 3.2kg and the mean birth length at 50.2cm which was comparable to the latest version of Korean National Growth Charts for children and adolescents released in 2017. CONCLUSIONS:Ko-CHENS results can assess various exposure burdens for the highly susceptible population and can strengthen the national pregnant woman and children environmental health management by providing policy guidance. KEYWORDS: National birth cohort, pregnancy outcome, delivery outcome