Birth outcomes of Koreans by birthplace of infants and their mothers, the United States versus Korea, 1995-2004

Prevalence of selected birth defects by maternal nativity status, United States, 1999-2007

OBJECTIVES

We investigated differences in prevalence of major birth defects by maternal nativity within racial/ethnic groups for 27 major birth defects.

METHODS

Data from 11 population-based birth defects surveillance systems in the United States including almost 13 million live births (approximately a third of U.S. births) during 1999-2007 were pooled. We calculated prevalence estimates for each birth defect for five racial/ethnic groups. Using Poisson regression, crude and adjusted prevalence ratios (aPRs) were also calculated using births to US-born mothers as the referent group in each racial/ethnic group.

RESULTS

Approximately 20% of case mothers and 26% of all mothers were foreign-born. Elevated aPRs for infants with foreign-born mothers were found for spina bifida and trisomy 13, 18, and 21, while lower prevalence patterns were found for pyloric stenosis, gastroschisis, and hypospadias.

CONCLUSIONS

This study demonstrates that birth defects prevalence varies by nativity within race/ethnic groups, with elevated prevalence ratios for some specific conditions and lower prevalence for others. More detailed analyses focusing on a broader range of maternal behaviors and characteristics are required to fully understand the implications of our findings.

Uncovering exposures responsible for birth season - disease effects: a global study

Objective

Birth month and climate impact lifetime disease risk, while the underlying exposures remain largely elusive. We seek to uncover distal risk factors underlying these relationships by probing the relationship between global exposure variance and disease risk variance by birth season.

Material and Methods

This study utilizes electronic health record data from 6 sites representing 10.5 million individuals in 3 countries (United States, South Korea, and Taiwan). We obtained birth month–disease risk curves from each site in a case-control manner. Next, we correlated each birth month–disease risk curve with each exposure. A meta-analysis was then performed of correlations across sites. This allowed us to identify the most significant birth month–exposure relationships supported by all 6 sites while adjusting for multiplicity. We also successfully distinguish relative age effects (a cultural effect) from environmental exposures.

Results

Attention deficit hyperactivity disorder was the only identified relative age association. Our methods identified several culprit exposures that correspond well with the literature in the field. These include a link between first-trimester exposure to carbon monoxide and increased risk of depressive disorder (R = 0.725, confidence interval [95% CI], 0.529-0.847), first-trimester exposure to fine air particulates and increased risk of atrial fibrillation (R = 0.564, 95% CI, 0.363-0.715), and decreased exposure to sunlight during the third trimester and increased risk of type 2 diabetes mellitus (R = −0.816, 95% CI, −0.5767, −0.929).

Conclusion

A global study of birth month–disease relationships reveals distal risk factors involved in causal biological pathways that underlie them.

Births to Parents with Asian Origins in the United States, 1992-2012

Despite a remarkable increase in Asian births in the U.S., studies on their birth outcomes have been lacking. We investigated outcomes of births to Asian parents and biracial Asian/White parents in the U.S. From the U.S. birth data (1992-2012), we selected singleton births to Korean, Chinese, Japanese, Filipino, Asian Indian, and Vietnamese. These births were divided into three groups; births to White mother/Asian father, Asian mother/White father, and births to the both ethnic Asian parents. We compared birth outcomes of these 18 subgroups to those of the White mother/White father group. Mean birthweights of births to the Asian parents were significantly lower, ranging 18 g to 295 g less than to the White parents. Compared to the rates of low birthweight (LBW) (4.6%) and preterm birth (PTB) (8.5%) in births to the White parents, births to Filipino parents had the highest rates of LBW (8.0%) and PTB (11.3%), respectively, and births to Korean parents had the lowest rates of both LBW (3.7%) and PTB (5.5%). This pattern of outcomes had changed little with adjustments of maternal sociodemographic and health factors. This observation was similarly noted also in births to the biracial parents, but the impact of paternal or maternal race on birth outcome was different by race/ethnicity. Compared to births to White parents, birth outcomes from the Asian parents or biracial Asian/White parents differed depending on the ethnic origin of Asian parents. The race/ethnicity was the strongest factor for this difference while other parental characteristics hardly explained this difference.

Seasonal Pattern of Preterm Births in Korea for 2000-2012

The aim of this study was to investigate a seasonal pattern of preterm births in Korea. Data were obtained from the national birth registry of the Korean Statistics Office and included all births in Korea during the period 2000-2012 (n = 6,310,800). Delivery dates were grouped by month of the year or by season (winter [December, January, February], spring [March, April, May], summer [June, July, August], and autumn [September, October, November]). The seasonal patterns of prevalence of preterm births were assessed. The rates of preterm births at 37 weeks were highest twice a year (once in winter and again in summer). The rates of preterm births increased by 13.9% in summer and 7.5% in winter, respectively, than in spring (OR, 1.139; 95% CI, 1.127-1.152, and OR, 1.075; 95% 1.064-1.087, respectively) after controlling for age, the educational level of the parents, maternal parity, and neonatal gender. The pattern for spontaneous preterm births < 34 weeks was similar. In Korea, a seasonal pattern of preterm births was observed, with peak prevalence in summer and winter. A seasonal pattern of preterm births may provide new insights for the pathophysiology of preterm births.

Neonatal and Infant Mortality in Korea, Japan, and the U.S.: Effect of Birth Weight Distribution and Birth Weight-Specific Mortality Rates

Difference in crude neonatal and infant mortality rates (NMR and IMR) among different countries is due to the differences in its two determinants: birth weight distribution (BWD) and birth weight-specific mortality rates (BW-SMRs). We aimed to determine impact of BWD and BW-SMRs on differences in crude NMR and IMR among Korea, Japan, and the U.S. Our study used the live birth data of the period 2009 through 2010. Crude NMR/IMR are the lowest in Japan, 1.1/2.1, compared to 1.8/3.2, in Korea, and 4.1/6.2, in the U.S., respectively. Japanese had the best BW-SMRs of all birth weight groups compared to the Koreans and the U.S. The U.S. BWD was unfavorable with very low birth weight (< 1,500 g) rate of 1.4%, compared to 0.6% in Korea, and 0.8% in Japan. If Koreans and Japanese had the same BWD as in the U.S., their crude NMR/IMR would be 3.9/6.1 for the Koreans and 1.5/2.5 for the Japanese. If both Koreans and Japanese had the same BW-SMRs as in the U.S., the crude NMR/IMR would be 2.0/3.8 for the Koreans and 2.7/5.0 for the Japanese. In conclusion, compared to the U.S., lower crude NMR or IMR in Japan is mainly attributable to its better BW-SMRs. Koreans had lower crude NMR and IMR, primarily from its favorable BWD. Comparing crude NMR or IMR among different countries should include further exploration of its two determinants, BW-SMRs reflecting medical care, and BWD reflecting socio-demographic conditions.

Korean immigrant women's lived experience of childbirth in the United States

OBJECTIVE

To understand Korean immigrant women's common experiences and practices of utilizing health care services in the United States during childbirth.

DESIGN

A qualitative interpretive phenomenological research design.

SETTING

Recruitment was conducted through advertisement on the MissyUSA.com website, which is the largest online community for married Korean women who live in North America.

PARTICIPANTS

A purposive sample of 15 Korean immigrant women who experienced childbirth in the United States within the past 5 years was recruited.

METHODS

Data were collected using semistructured telephone interviews and were analyzed using the Heideggerian hermeneutical methodology.

RESULTS

During childbirth in the United States, participants faced multifaceted barriers in unfamiliar sociocultural contexts yet maintained their own cultural heritages. They navigated the unfamiliar health care system and developed their own strategies to overcome barriers to health care access. Korean immigrant women actively sought health information on the Internet and through social networking during childbirth.

CONCLUSIONS

Korean immigrant women selectively accepted new cultural beliefs with some modifications from their own cultural contexts and developed their own distinct birth cultures. Understanding a particular culture and respecting women's traditions, beliefs, and practices about their childbirth could help nurses to provide culturally sensitive care.

The impact of neonatal care resources on regional variation in neonatal mortality among very low birthweight infants in Korea

BACKGROUND

Faced with extremely low fertility rates and increasing numbers of low-birthweight births in Korea, we examined the factors affecting the mortality of very-low-birthweight (VLBW) infants in Korea.

METHODS

A survey was conducted in 91 of 93 hospitals providing neonatal intensive care in Korea in 2009. Data included information on number of neonatal intensive care unit (NICU) beds, medical workforce, resources in the NICU, birth and death.

RESULTS

There was approximately one NICU per 4888 births, one NICU bed per 355 births, one mechanical ventilator per 739 births, one incubator per 327 births and one board-certified neonatologist per 4683 births. Regional disparity existed in neonatal care resources and consequently in mortality rates. VLBW infants' mortality was related to the NICU facility level, volume of VLBW infants and geographic regions. The capital city, Seoul, has the best NICU facilities and workforce, and the least mortality. Overall mortality rates before hospital discharge for <750, 750-999 and 1000-1499 g were 44.8%, 20.4% and 6.5% respectively. There was a two to threefold difference in the mortality rates across the regions. However, following adjustments for NICU facility level and volume of VLBW infants admissions, regional difference in mortality rates was markedly reduced in the <750 g and disappeared in the larger VLBW groups.

CONCLUSIONS

Regional disparity in mortality of VLBW infants in Korea is most marked in the lowest-birthweight group, <750 g. This disparity is primarily due to lack of resources for neonatal intensive care in most of provincial areas.

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

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.