Secular Trends of Multiple Birth Rate in Korea: 1981–2017

PURPOSE: To determine the secular trend of the multiple birth rate in Korea from 1981 to 2017. METHODS: This study used birth certificate data covering the years 1981–2017 (20,948,901 births), provided by Statistics Korea. The impact of assisted reproductive technologies (ART) on multiple birth was analyzed by examining data prior to and after the introduction of ART and the national support program for infertile couples in South Korea. The odds ratio (OR) and 95% confidence intervals were calculated to describe the secular trend in the multiple birth rate per 100 births. RESULTS: During this period, the multiple birth rate per 100 births increased by 277 percent from 1.031 to 3.891, the twin birth rate increased from 1.013 to 3.807 (275%), and the triplet birth rate increased from 0.018 to 0.084 (363%). The secular trend of the multiple birth rate remained in the 1.000 level during 1981–1991, but has been rising steadily since 1992. The average increment of the multiple birth rate was 3.9% annually from 1981 through 2017 (peaking at more than 10 percent during 2006–2007). Prior to the introduction of ART in Korea (1981–1984), the multiple birth rate was 1.007, but after its introduction, the multiple birth rate was 1.005 in 1985–1989 (OR, 0.998; 95% confidence interval, 0.982–1.014), 1.084 in 1990–1994 (1.007; 1.060–1.094), 1.891 in 2000–2004 (1.894; 1.866–1.922), 3.127 in 2010–2014 (3.173; 3.129–3.217), and 3.811 in 2015–2017 (3.893; 3.835–3.952). CONCLUSION: Over the past three decades, multiple births have risen dramatically in Korea, primarily due to the increasingly widespread use of fertility therapies, and the delayed age of childbearing. There is a need for more research to understand the factors contributing to multiple births, and the national birth registration systems ought to be reformed to monitor whether multiple births originated spontaneously or from assisted-conception.

Percentile Distributions of Birth Weight according to Gestational Ages in Korea (2010-2012)

The Pediatric Growth Chart (2007) is used as a standard reference to evaluate weight and height percentiles of Korean children and adolescents. Although several previous studies provided a useful reference range of newborn birth weight (BW) by gestational age (GA), the BW reference analyzed by sex and plurality is not currently available. Therefore, we aimed to establish a national reference range of neonatal BW percentiles considering GA, sex, and plurality of newborns in Korea. The raw data of all newborns (470,171 in 2010, 471,265 in 2011, and 484,550 in 2012) were analyzed. Using the Korean Statistical Information Service data (2010-2012), smoothed percentile curves (3rd-97th) by GA were created using the lambda-mu-sigma method after exclusion and the data were distinguished by all live births, singleton births, and multiple births. In the entire cohort, male newborns were heavier than female newborns and singletons were heavier than twins. As GA increased, the difference in BW between singleton and multiples increased. Compared to the previous data published 10 years ago in Korea, the BW of newborns 22-23 gestational weeks old was increased, whereas that of others was smaller. Other countries' data were also compared and showed differences in BW of both singleton and multiple newborns. We expect this updated data to be utilized as a reference to improve clinical assessments of newborn growth.

Secular trends in the rate of low birth weight in Brazilian State Capitals in the period 1996 to 2010 / Tendência secular da taxa de baixo peso ao nascer nas capitais brasileiras de 1996 a 2010 / Tendencia secular de la tasa de bajo peso al nacer en las capitales brasileñas de 1996 a 2010

Secular trends in rates of low birth weight in Brazilian state capital cities were evaluated for the period 1996 to 2010 using joinpoint regression models. The rates were calculated using data from the Live Births Information System. Newborns weighing less than 500g were excluded. Only data for capital cities was included since under-registration of births in these cities is lower and new trends can be detected earlier. There was a significant increase in the rate of low birth weight in the Brazilian capitals of the North Region, Northeast Region, South Region and Southeast Region up to 2003/2004, stabilizing thereafter. In the capitals of the Center-west Region the rate increased throughout the whole study period. The rate of low birth weight was higher in the capitals of the more developed regions. The rate of multiple births increased significantly in all Brazilian capitals, while the stillbirth rate decreased and showed a negative correlation with the rate of low birth weight. The increase in the rate of low birth weight may be partially explained by the increase in multiple births, an increase in the birth of infants weighing 500 to 999g and by the reduction in the stillbirth rate.

A tendência secular da taxa de baixo peso ao nascer de 1996 a 2010 nas capitais brasileiras foi avaliada utilizando-se modelos de regressão joinpoint. As taxas foram calculadas a partir do Sistema de Informações sobre Nascidos Vivos, excluindo-se recém-nascido com peso < 500g. Foram incluídos apenas dados das capitais, onde o sub-registro é menor e novas tendências podem ser detectadas mais precocemente. A taxa de baixo peso ao nascer aumentou significantemente nas capitais brasileiras das regiões Norte, Nordeste, Sul e Sudeste até 2003/2004, tendo se estabilizado a partir de então. Nas capitais da Região Centro-oeste a taxa aumentou ao longo de todo o período. A taxa de baixo peso ao nascer foi maior nas capitais das regiões mais desenvolvidas. A taxa de partos múltiplos aumentou significantemente nas capitais brasileiras. A taxa de natimortalidade diminuiu e apresentou correlação negativa com a taxa de baixo peso ao nascer. Parte do aumento na taxa de baixo peso ao nascer pode ser explicado pelo aumento na taxa de nascimentos múltiplos e pelo nascimento de recém-nascido pesando de 500g a 999g e pela redução da taxa de natimortalidade.

La tendencia secular de la tasa de bajo peso al nacer de 1996 a 2010 en las capitales brasileñas se evaluó utilizando modelos de regresión joinpoint. Las tasas se calcularon a partir del Sistema de Información sobre Nacidos Vivos, excluyéndose recién nacidos con un peso < 500g. Fueron incluidos solamente datos de las capitales, donde el sub-registro es menor y las nuevas tendencias pueden ser detectadas más precozmente. La tasa de bajo peso al nacer aumentó significantemente en las capitales brasileñas de las regiones Norte, Nordeste, Sur y Sudeste hasta 2003/2004, habiéndose estabilizado a partir de entonces. En las capitales de la Región Centro-oeste la tasa aumentó a lo largo de todo el período. La tasa de bajo peso al nacer fue mayor en las capitales de las regiones más desarrolladas. La tasa de partos múltiples aumentó significantemente en las capitales brasileñas. La tasa de natimortalidad disminuyó y presentó una correlación negativa con la tasa de bajo peso al nacer. Una parte del crecimiento en la tasa de bajo peso al nacer puede ser explicada por el aumento en la tasa de nacimientos múltiple, por el nacimiento de recién nacidos pesando de 500g a 999g y por la reducción de la tasa de natimortalidad.

The changing trends in live birth statistics in Korea, 1970 to 2010 / 소아과

Although Korean population has been growing steadily during the past four decades, the nation is rapidly becoming an aging society because of its declining birth rate combined with an increasing life expectancy. In addition, Korea has one of the lowest fertility rates in the world due to fewer married couples, advanced maternal age, and falling birth rate. The prevalence of low birth weight infants and multiple births has been increased compared with the decrease in the birth rate. Moreover, the number of congenital anomalies is expected to increase due to the advanced maternal age. In addition, the number of interracial children is expected to increase due to the rise in the number of international marriages. However, the maternal education level is high, single-mother birth rate is low, and the gender imbalance has lessened. The number of overweight babies has been decreased, as more pregnant women are receiving adequate prenatal care. Compared to the Asian average birth weight, the average birth weight is the highest in Asia. Moreover, the rate of low birth weight infants is low, and infant mortality is similarly low across Asia. Using birth data from Statistics Korea and studies of birth outcomes in Korea and abroad, this study aimed to assess the changes in maternal and infant characteristics associated with birth outcomes during the past four decades and identify necessary information infrastructures to study countermeasures the decrease in birth rate and increase in low birth weight infants in Korea.

The changing trends in live birth statistics in Korea, 1970 to 2010 / 소아과

Although Korean population has been growing steadily during the past four decades, the nation is rapidly becoming an aging society because of its declining birth rate combined with an increasing life expectancy. In addition, Korea has one of the lowest fertility rates in the world due to fewer married couples, advanced maternal age, and falling birth rate. The prevalence of low birth weight infants and multiple births has been increased compared with the decrease in the birth rate. Moreover, the number of congenital anomalies is expected to increase due to the advanced maternal age. In addition, the number of interracial children is expected to increase due to the rise in the number of international marriages. However, the maternal education level is high, single-mother birth rate is low, and the gender imbalance has lessened. The number of overweight babies has been decreased, as more pregnant women are receiving adequate prenatal care. Compared to the Asian average birth weight, the average birth weight is the highest in Asia. Moreover, the rate of low birth weight infants is low, and infant mortality is similarly low across Asia. Using birth data from Statistics Korea and studies of birth outcomes in Korea and abroad, this study aimed to assess the changes in maternal and infant characteristics associated with birth outcomes during the past four decades and identify necessary information infrastructures to study countermeasures the decrease in birth rate and increase in low birth weight infants in Korea.

Mortalidad perinatal en gestaciones múltiples: Hospital Miguel Servet, Zaragoza, España: 2000-2009 / Perinatal mortality in multiple pregnancies: Hospital Miguel Servet, Zaragoza, España: 2000-2009

Objetivos: Evaluar la mortalidad perinatal (MP) de las gestaciones múltiples del Hospital Miguel Servet de Zaragoza (2000-2009). Método: Análisis, sobre un total de 44.401 recién nacidos (RN) >500 gramos, de 92 nacidos muertos ó fallecidos antes de los 28 días de vida procedentes de gestaciones múltiples. Los datos se recogieron en un formulario siguiendo las recomendaciones de la FIGO y la novena Clasificación Internacional de Enfermedades (CIE). Resultados: La MP ampliada global fue de 40,42/1000 nacidos. Analizada por el número de RN, la MP de los embarazos gemelares fue 34,65/1000 nacidos y la de las gestaciones triples 80,65/1000. La mortalidad fetal fue 11,86/1000 nacidos y la neonatal (MN) 28,56/1000 nacidos vivos. La MP estándar fue 14,06/1000. Esta MP constituye el 22,89 por ciento de la MP total del Hospital, y la MN de los múltiples el 35,33 por ciento de la mortalidad neonatal total. Un 97,83 por ciento fueron pretérminos; 72,83 por ciento fueron <1000 gramos y 88,05 por ciento <1500 gramos. La causa última fue inmadurez extrema, <1000 gramos (72,83 por ciento). Hubo un 18,48 por ciento de rotura prematura (RPM) de membranas, 17,39 por ciento de partos pretérminos espontáneos sin otra causa aparente, y 13,04 por ciento de malformaciones congénitas y cromosomopatías. Conclusión: La MP en múltiples está gravada por la prematuridad, y el bajo peso extremo. La MP de ambos gemelos ocurre en el bajo peso extremo (87,50 por ciento <1000 gramos), y sus causas más frecuentes son RPM (21,88 por ciento) con corioam-nionitis (12,50 por ciento) y el síndrome de transfusión feto-fetal (18,76 por ciento).

Objective: To evaluate Hospital Miguel Servet perinatal mortality (PM) in multiple pregnancies (2000-2009), valuing its evolution and distribution according to gestational age and birth weight. Maternal and fetal causes are analized. Methods: 44,401 newborns of >500 grams or 22 weeks gestational age, were studied. The total number of perinatal deaths in multiple pregnancies was 92 containing late neonatal deaths (to 28 days of live). The data for each case of perinatal mortality were recorded in a form following FIGO recommendations and the 9th International Classification Diseases. Results: Extended PM rate in multiple pregnancies was 40.42/1000 newborns, PM in twins was 34.65/1000, and in triplet births 80.65/1000. Fetal mortality was 11.86/1000 newborns and neonatal mortality 28.56/1000 live births. Standard PM was 14.06/1000 newborns. The MP of the multiple pregnancies was the 22.89 percent of total MP, and multiple pregnancies neonatal mortality 35.33 percent of total neonatal mortality. According to gestational age, 97.83 percent were preterm deliveries (90 newborns). Considering birth weights, 72.83 percent were extremely low birth weight (<1000 grams), and 88.05 percent were <1500 grams. Main cause of death was extreme immaturity (<1000 grams). Premature rupture of membranes (PROM) was presented in 18.48 percent, of the cases, spontaneous preterm labor without apparent cause in 17.39 percent, and congenital malformations and chromosomopaties (13.04 percent). Conclusions: PM in multiple pregnancies is encumbered by prematurity and extremely low birth weight. PM in both twins was associated with extremely low birth weight (87.50 percent < 1000 grams), and main causes of death were PROM (21.88 percent) with chorioamnionitis (12.50 percent), and twin-to-twin transfusion syndrome (18.76 percent).

Recent Trends in the Incidence of Multiple Births and Its Consequences on Perinatal Problems in Korea

The aim of this study was to survey multiple birth data and to analyze the recent trends of multiple births and its consequences on perinatal problems in Korea from 1991 to 2008. Data were obtained from the Korean Statistical Information Service. The total number of multiple births showed increasing trends. The multiple birth rate was maintained within less than 10.0 for the decade from 1981 to 1990. However, it increased gradually to reach 27.5 in 2008. The maternal age for multiple births was higher than for total live births. The mean birth weight of the total live births was 3.23 kg; for the multiple births it was 2.40 kg in 2008. The incidence of low birth weight infants (LBWI) among total live births was 3.8% in 2000 and 4.9% in 2008. For multiple births it was 49.2% and 53.0% during the same years. The incidence of preterm births among total live births was 3.8% in 2000 and 5.5% in 2008; for the multiple births it was 38.3% and 51.5% during the same years. The incidence of multiple births and its consequences on perinatal problems (preterm, LBWI, and advanced-maternal age) have been increased steadily over the last two decades in Korea.

Multiple births conceived by assisted reproductive technology in Korea / 소아과

PURPOSE: The recent trends of multiple births (MBs) conceived by assisted reproductive technology (ART) in Korea were analyzed as well as the relationship with maternal age, especially advanced maternal age. METHODS: Data were obtained from the Korean Statistical Information Service and annual ART reports from the ART committee of the Korean Society of Obstetrics and Gynecology. RESULTS: MBs increased from the early 1990s; there was a 275% increase by 2008. The number of total live births was 448,153 and MBs accounted for 10,767; the MB rate was 24.0% in 2006. Among 2,326 deliveries conceived by ART, multiple deliveries accounted for 786 (33.8%). The total number of live births with ART was 3,125 and 1,585 (50.7%) of them were MBs. During 2006, 14.7% of the entire MBs in Korea were associated with ART. The proportion of women of advanced maternal age was much higher in the ART group than in the total live birth group. CONCLUSION: MBs in women of advanced maternal age have been increasing in Korea with the use of ART. The results of this study showed that ART was a significant factor associated with the increase in MBs in Korea.

Comparison of Mortality and Morbidity in Multiple versus Singleton Very Low Birth Weight Infants in A Neonatal Intensive Care Unit

Multiple births in Korea have been increased recently as a consequence of increased infertility due to advancing maternal age at first birth, and increased use of assisted reproductive technology. Multiples suffer higher mortality and morbidity than singletons. However, it is not clear whether preterm multiple very low birth weight infants (VLBWI) suffer higher mortality and morbidity than comparable singletons. We evaluated 266 singleton and 113 multiple VLBWI to determine whether mortality and morbidity in multiple VLBWI were higher than those in comparable singletons. The rate of in vitro ertilization and cesarean section were significantly higher in multiples than singletons. The total and the adjusted mortality with gestational age and birth weight were not significantly different between the two groups. Maternal age and the incidence of respiratory distress syndrome, patent ductus arteriosus, bronchopulmonary dysplasia, intracranial hemorrhage (grade> or=3), cystic periventricular leukomalacia, and retinopathy of prematurity (stage> or=3) were not significantly different between the two groups, and the incidence of abnormal brainstem auditory evoked potential was higher among the singletons. These results suggest that multiple VLBWI do not suffer higher mortality or morbidity than comparable singletons.

Study on Multiple Birth Based on Birth Certificate Data / 대한산부인과학회잡지

OBJECTIVE: Multiple birth implicates the important health and social problems such as preterm birth, low birth weight, high perinatal mortality, and increased medical cost. This study was performed to investigate the multiple birth rate in Korea using the birth certificate data. METHODS: Retrospective review and analysis of data from Korean birth certificate in 1996. RESULTS: Multiple birth rate was 1.4% of total births(683,043 cases). Mean birth weight was 3.29+/-0.47kg for singleton birth and 2.57+/-0.58kg for multiple birth. Mean gestational age was 39.56+/-1.32 weeks for singleton birth and 37.47+/-2.41 weeks for multiple birth. Rate of low birth weight (< 2.5kg) was 14 times higher for multiple birth compared with that of singleton birth, and rate of preterm birth(< 37 weeks) was 10 times higher. Multiple logistic regression analysis was performed to examine the relationship between multiple birth and selected variables including maternal age, job and birth order. As the odds ratio(OR) was 2.47(95% CI: 2.34 - 2.59, p<0.001) for the second birth, and 5.31(95% CI: 4.99 - 5.65, p<0.001) for the third and over birth compared with the first birth, there was a significant correlation between multiple birth and birth order. CONCLUSIONS: Based on the birth certificate data in 1996, the incidence of twin and higher order multiple birth was 1.7%, and a significant correlation between multiple birth and birth order was revealed. Further studies are necessary to elucidate the etiology and prognosis of multiple birth and the developmental problems from birth to adolescence.

A clinical study on twin

No abstract available.