Young Shin Kim1, Minku Kang1, Young June Choe2, Joohon Sung3, Ji Yeon Lee4, Seung-Ah Choe5,6. 1. Department of Preventive Medicine, Korea University College of Medicine, Seoul, 02841, South Korea. 2. Department of Pediatrics, Korea University Anam Hospital, Seoul, 02841, South Korea. 3. Department of Public Health Science, Graduate School of Public Health, Seoul National University, Seoul, 08826, Korea. 4. Department of Obstetrics and Gynecology, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea. 5. Department of Preventive Medicine, Korea University College of Medicine, Seoul, 02841, South Korea. seungah@korea.ac.kr. 6. Division of Life Sciences, Korea University, 02841, Seoul, South Korea. seungah@korea.ac.kr.
Abstract
Twins involve a higher risk of perinatal complications compared to singletons. We compared the risk of under five mortality between twins and singletons among late preterm and term births. The national birth data of South Korea pertaining to the years 2010-2014 linked with the mortality record of children aged under 5 years in 2010-2019 was analyzed. The final study population was 2,199,632 singletons and 62,351 twins. We conducted a survival analysis of under-five mortality with adjustment for neonatal and familial factors. Overall under-five mortality rates during the study period were 3.6 and 2.0 for twins and singletons, respectively. Although the unadjusted overall under-five mortality was higher in twins (hazard ratio [HR] = 1.80, 95% confidence interval [CI]: 1.57, 2.06, overall risk), twin birth was associated with comparable or lower risk (HR = 0.70, 95% CI: 0.58, 0.85, overall; 0.70, 95% CI: 0.56, 0.87, excluding neonatal mortality; 0.59, 95% CI: 0.40, 0.86, excluding infant mortality) after controlling for both neonatal and familial factors. Twins born at a gestational age of 34-35 weeks showed a generally lower risk of under-five mortality than their singleton counterparts, regardless of model specification. Conclusion: Among late preterm and term birth, under-5-year mortalities for twins were lower than singleton births when adjusted for neonatal and familial risk factors. This highlights the differential implication of gestational age at birth between twin and singleton in the child mortality.
Twins involve a higher risk of perinatal complications compared to singletons. We compared the risk of under five mortality between twins and singletons among late preterm and term births. The national birth data of South Korea pertaining to the years 2010-2014 linked with the mortality record of children aged under 5 years in 2010-2019 was analyzed. The final study population was 2,199,632 singletons and 62,351 twins. We conducted a survival analysis of under-five mortality with adjustment for neonatal and familial factors. Overall under-five mortality rates during the study period were 3.6 and 2.0 for twins and singletons, respectively. Although the unadjusted overall under-five mortality was higher in twins (hazard ratio [HR] = 1.80, 95% confidence interval [CI]: 1.57, 2.06, overall risk), twin birth was associated with comparable or lower risk (HR = 0.70, 95% CI: 0.58, 0.85, overall; 0.70, 95% CI: 0.56, 0.87, excluding neonatal mortality; 0.59, 95% CI: 0.40, 0.86, excluding infant mortality) after controlling for both neonatal and familial factors. Twins born at a gestational age of 34-35 weeks showed a generally lower risk of under-five mortality than their singleton counterparts, regardless of model specification. Conclusion: Among late preterm and term birth, under-5-year mortalities for twins were lower than singleton births when adjusted for neonatal and familial risk factors. This highlights the differential implication of gestational age at birth between twin and singleton in the child mortality.