Multiple birth rates of Korea and fetal/neonatal/infant mortality in multiple gestation.

Hyun Sun Ko,Sae Kyung Choi,Yong-Gyu Park,Jeong Ha Wie,In Yang Park,Jong Chul Shin,Jacobus P Van Wouwe

doi:10.1371/journal.pone.0202318

Abstract

ObjectiveThis study was conducted to analyze recent trends of multiple birth rates (MBR) and fetal/neonatal/infant mortalities according to the number of gestations in Korea.MethodsData from 2009 to 2015 of live births, infant deaths and stillbirths were obtained from the Korean Vital Statistics. Neonatal mortality rate (NMR), infant mortality rate (IMR), and fetal mortality rate (FMR) in singleton, twin and triplet pregnancies were analyzed according to gestational period (GP; ≤ 23, 24–27, 28–31, and 32–36 weeks).ResultsFrom 2009 to 2015, twin and triplet birth rates increased 34.5% and 154.3%, respectively. In twin births, NMR and FMR have been decreased significantly (from 10.92 to 8.62, p = 0.034 and from 41.00 to 30.55, p< 0.001, respectively), but IMR did not show significant decrease. There was no significant change of NMR, IMR, and FMR, in triplet births. Overall, in singleton, twin, and triplet births, NMR was 1.26 ± 0.09, 10.6 ± 1.12, and 34.32 ± 11.72, respectively, and IMR was 2.38 ± 0.26, 14.52 ± 1.38, and 41.13 ± 12.2, respectively. FMRs were 12 ± 1.73, 35.99 ± 3.55, and 88.85 ± 16.55, respectively, in singleton, twin, and triplet pregnancies. In spite of decreasing trends in overall mortalities, the odds ratios of NMRs and IMRs in 2015 were approximately 9-fold and 6-fold higher, respectively, in twin births, and approximately 37-fold and 20-fold higher, respectively, in triplet births, than those in singleton births. There were no significant differences in odds ratios of NMRs and IMRs at GP 32–36 among single, twin, and triplet births, although the odds ratios of FMR at GP 32–36 in triplet gestation was significantly higher than those in singleton and twin gestation.ConclusionNeonatal/infant mortality in multiple births is still significantly high, which is mainly related with preterm birth. Close fetal monitoring is needed to prevent fetal death in triplet pregnancies, after 32 gestational weeks.

Highlights

Advanced maternal age and the use of assisted reproductive technology (ART) procedures are considered as major factors associated with the increasing trend of multiple births [1,2,3]
There was no significant change of neonatal mortality rate (NMR), infant mortality rate (IMR), and fetal mortality rates (FMR), in triplet births
There were no significant differences in odds ratios of NMRs and IMRs at gestational period (GP) 32– 36 among single, twin, and triplet births, the odds ratios of FMR at GP 32–36 in triplet gestation was significantly higher than those in singleton and twin gestation

Summary

Introduction

Advanced maternal age and the use of assisted reproductive technology (ART) procedures are considered as major factors associated with the increasing trend of multiple births [1,2,3]. Double and higher order embryo transfer is associated with a higher risk of stillbirth, neonatal/ infant morbidity and mortality, when compared with single embryo transfer (SEF), mainly because multiple births are associated with preterm birth. Because preterm birth is related with neonatal/infant mortality and morbidity, and predisposes to higher risks of chronic diseases and mortality later in life [4, 5], many countries are making efforts to reduce multiple birth rate (MBR), which have shown improved perinatal outcomes [6]. MBR in Korea has been increased steadily until 2008 and it was related with increased incidence of preterm birth. Investigation of fetal mortality rates (FMR) during 2nd and 3rd trimester in multiple pregnancies can be valuable for planning antenatal care in multiple pregnancies, as well as for estimating benefits and risks related with a selective multifetal reduction in multiple pregnancies

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Results

Conclusion