• Journal of Preventive Medicine and Public Health
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• v.53 no.5
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• pp.371-380
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• 2020

Objectives: This study investigated the effects of socio-demographic factors on the decreasing trend in the sex ratio at birth from 1997 to 2017 in Korea. Methods: Data from 10 349 602 live births registered with Statistics Korea from 1997 to 2017 were analyzed. The secondary sex ratio (SSR), defined as the ratio of male to female live births, during the study period (1997-1999 [phase I], 2000-2002 [phase II], 2003-2005 [phase III], 2006-2008 [phase IV], 2009-2011 [phase V], 2012-2014 [phase VI], and 2015-2017 [phase VII]) was calculated according to selected socio-demographic factors, such as parental age, education, occupation, and birth order. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals for a male birth after adjusting for potential confounders. Results: The SSR gradually decreased from 1.10 (in 1998-2000 and 2002) to 1.05 (in 2013-2016). While a decreasing trend in the SSR was not noted among first births, male-biased sex ratios were prominent among third and higher-order births, for which the highest SSR was 1.46 in 1998. Higher birth order was significantly associated with an excess of male births in phases I-VI (≥third vs. first, OR range, 1.03 to 1.35). Advanced maternal age was significantly associated with an excess of female births in phases II, III, and V (≥40 vs. 20-24 years, OR range, 0.92 to 0.95). Conclusions: This study demonstrated that advanced maternal age and reduction of the artificially-biased SSR among third and higher-order births may partially explain the decreasing trend in the SSR from 1997 to 2017 in Korea.

• Korea journal of population studies
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• v.17 no.2
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• pp.98-115
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• 1994

This study is attempting to examine the possible determinants of the rise of the sex ratio at birth from 106 to 110 in past decade in Taiwan. The basic hypothesis for the sudden rise of the sex ratio at birth is due to a combination of prenatal sex determination and abortion. The reasoning for this hypothesis involves three types of considerations - motivation, norm, and access. The theory is evaluated by analyzing data from birth registration and a large and representative sampie of Taiwanese wives of childbearing age. The empirical data seem to support the theoretical preposition and the basic hypothesis that the rise of the sex ratio at birth in Taiwan is due to a combination of prenatal sex determination and abortion. There is striking evidence of son-preference in the rise of the sex ratio at birth in higher birth order. In 1990 the sex ratio was 119 for third births and 128 for fourth and fifth births compared to the expected 106. Also, the 1991 KAP data indicated that women who have only daughters but no any son are more likely to make prenatal sex screening and terminate their pregnancies in male live births at higher birth order. Obviously, genetic diagnosis through chorionic villus sampling which was available in recent years was misused for prenatal sex determination and sex selective abortion.

• Korea journal of population studies
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• v.7 no.1
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• pp.78-123
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• 1984

This study is attempting to examine the possible determinants of the rise of the sex ratio at birth from 106 to 110 in past decade in Taiwan. The basic hypothesis for the sudden rise of the sex ratio at birth is due to a combination of prenatal sex determination and abortion. The reasoning for this hypothesis involves three types of considerations - motivation, norm, and access. The theory is evaluated by analyzing data from birth registration and a large and representative sampie of Taiwanese wives of childbearing age. The empirical data seem to support the theoretical preposition and the basic hypothesis that the rise of the sex ratio at birth in Taiwan is due to a combination of prenatal sex determination and abortion. There is striking evidence of son-preference in the rise of the sex ratio at birth in higher birth order. In 1990 the sex ratio was 119 for third births and 128 for fourth and fifth births compared to the expected 106. Also, the 1991 KAP data indicated that women who have only daughters but no any son are more likely to make prenatal sex screening and terminate their pregnancies in male live births at higher birth order. Obviously, genetic diagnosis through chorionic villus sampling which was available in recent years was misused for prenatal sex determination and sex selective abortion.

• Journal of Preventive Medicine and Public Health
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• v.42 no.2
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• pp.143-150
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• 2009

Objectives : South Korea has experienced unprecedented ups and downs in the sex ratio at birth(SRB), which has been a unique phenomenon in the last two decades. However, little is known about socioeconomic factors that influence the SRB. Employing the diffusion theory by Rogers, this study was undertaken to examine the trends in social variations in the SRB from 1981 to 2004 in Korea. Methods : The data was taken from Vital Birth Statistics for the period from 1981-2004. We computed the annual male proportion of live births according to the parental education(university, middle/high school, primary) and occupation(non-manual, manual, others). Logistic regression analysis was employed to estimate the odds ratios of male birth according to social position for the equidistant three time periods(1981-1984, 1991-1994, and 2001-2004). Results : An increased SRB was detected among parents with higher social position before the mid 1980s. Since then, however, a greater SRB was found for the less educated and manual jobholders. The inverse social gradient for the SRB was most prominent in early 1990s, but the gap has narrowed since the late 1990s. The mother's socioeconomic position could be a sensitive indicator of the social variations in the sex ratio at birth. Conclusions : Changes in the relationship of parental social position with the SRB were detected during the 1980-2004 in Korea. This Korean experience may well be explained by diffusion theory, suggesting there have been socioeconomic differences in the adoption and spread of sex-detection technology.

• The Korean Journal of Applied Statistics
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• v.22 no.2
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• pp.365-373
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• 2009

Since 1990, identifying the sex of fetus and illegal abortion has brought the sex ratio imbalance at birth in Korea due to a notion of preferring a son to a daughter, socio-economic development, population policy, and so forth. Although there have been many researches such as time series analysis and region difference analysis to monitor this sex ratio imbalance, they have a defect that time and space could not be included in the analysis simultaneously. This study analyzes the sex ratio imbalance at birth, taking into account time and region at the same time. The analysis considered the numbers of male and female babies, who were born as the third or latter in their families, in 2000 and 2001 at 234 Gu / Si / Goon administrative districts. Here, we suggest a mixture model of binomial distributions, assuming heterogeneous populations. The estimation of the location parameters, weights and correlation coefficient of the mixture model is conducted by the EM algorithm, and the heterogeneity of the regions is expressed as a picture using ArcView GIS.

• Journal of Embryo Transfer
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• v.24 no.1
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• pp.15-19
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• 2009

This study was carried out to collect the basic data about gestation lengths and offspring's birth weights and sex ratio of the dairy recipients transferred with Hanwoo IVF embryos. Blastocysts cultured for $7{\sim}8$ days were transferred to 96 and 167 heads for the basic data about gestation length and offspring's birth weight and sex ratio of the dairy recipients, respectively. The gestation lengths of the dairy recipients transferred with Hanwoo IVF embryos were $287.3{\pm}11.2$ ($257{\sim}311$) and $284.1{\sim}7.7$ ($266{\sim}295$) days in male and female of the offspring, respectively. The gestation lengths of the recipients were $290.7{\pm}10.4$, $285.8{\pm}3.4$, $280.0{\pm}9.3$ and $286.1{\pm}7.9$ days in spring, summer, autumn and winter of the calving season, respectively, and were significantly different among the calving season (p<0.05). The birth weights of male and female calves were $25.5{\pm}2.4$ ($21{\sim}30$) and $26.3{\pm}3.9$ ($21{\sim}40$ kg in offsprings of the dairy recipients transferred with Hanwoo IVF embryos, respectively. The sex ratio was 90.7 in the offsprings of the dairy recipients transferred with Hanwoo IVF embryos.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.4
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• pp.447-451
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• 2012

The objective of this research was to determine the prevalence, risk factors and consequent effect of dystocia on lactation performance in Holstein dairy cows in Iran. The data set consisted of 55,577 calving records on 30,879 Holstein cows in 30 dairy herds for the period March 2000 to April 2009. Factors affecting dystocia were analyzed using multivariable logistic regression models through the maximum likelihood method in the GENMOD procedure. The effect of dystocia on lactation performance and factors affecting calf birth weight were analyzed using mixed linear model in the MIXED procedure. The average incidence of dystocia was 10.8% and the mean (SD) calf birth weight was 42.13 (5.42) kg. Primiparous cows had calves with lower body weight and were more likely to require assistance at parturition (p<0.05). Female calves had lower body weight, and had a lower odds ratio for dystocia than male calves (p<0.05). Twins had lower birth weight, and had a higher odds ratio for dystocia than singletons (p<0.05). Cows which gave birth to a calf with higher weight at birth experienced more calving difficulty (OR (95% CI) = 1.1(1.08-1.11). Total 305-d milk, fat and protein yield was 135 (23), 3.16 (0.80) and 6.52 (1.01) kg less, in cows that experienced dystocia at calving compared with those that did not (p<0.05).

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.4 no.1
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• pp.46-53
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• 1993

To find some involvement of environmental factors in autism, season of birth, birth order, and maternal age at birth of autistic children were investigated Total number of clinical outpatient autistic children was 357, which consisted of 319 male and 38 female, then male-to-female sex ratio was 8.4 to 1, and all subjects were born during $1986{\sim}1988.$ These data were compared with those of controlled general populations. The results were as follows : 1) In monthly and seasonal distributions of birth, autistic children were not different from normal control 2) Comparing with control group by Slater's and Greenwood-Yule's birth order calculation methods, there was no significant difference in birth order of autistic children 3) The maternal ages at birth in autistic group were significantly higher than those of control group(P<01) 4) High-risk pregnancies were significantly frequent in autistic group compared with control group(p<01)Our study supported the idea that at least some environmental factors, especially at-risk pregnancy, are involved in autism causation.

• Journal of Yeungnam Medical Science
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• v.4 no.2
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• pp.97-103
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• 1987

Neonatal and obstetrical problems related to the low birth weight infants were evaluated by a retrospective review of the medical records of the 186 low birth weight infants born at Yeungnam-University Hospital during 3 years and 8 months from May 1, 1983 to February 28, 1987. The results were as follows ; 1. The incidence of the low birth weight infants was 4.98% among 3803 live births. 2. Male to female ratio was 1.02:1. 3. The incidence of the low birth weight infants was lowest in mothers of 25 to 29 years, increased in mothers of 19 years of less and 30 to 39 years significantly. 4. There was no difference in the incidence of low birth weight infants between primiparous and multiparous mothers. 5. Common obstetrical complications associated with low weight infants were multiple pregnancy, toxemia and premature rupture of membrane in order of frequency. 6. Common neonatal problems in low birth weight infants were jaundice, idiopathic respiratory, distress syndrome, asphyxia and metabolic dfrangement such as hypocalcemia and hypoglycemia in order of frequency.

• Journal of Nutrition and Health
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• v.29 no.3
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• pp.267-277
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• 1996

Effect of DHA-rich fish oil on brain development and learning ability has been studied in Sprague Dawley rats. Female rats were fed experimental diets containing either corn oil fish oil at 10%(w/w) level throughout the gestation and lactation. Corn oil was added in fish oil diet to supply essential fatty acid at 2.3% of the calories. All male pups were weaned to the same diets of dams at 21-days after birth. Plasma fatty acid composition was analyzed for dams and pups at 21-days, 28-days and 22-weeks after birth. The analysis of DNA and fatty acid profile in the brain were undertaken at birth, 3, 7, 14, 21, 28 days and 22 weeks after birth and learning ability was tested at 18-20 weeks of age. Regardless of dietary fats, arachidonic acid(AA) and docosahexaenoic acid(DHA) were the principal polyunsaturated fatty acids in the brain. Rats fed CO diet showed a continouus increase of AA content in the brain from 10.9%(at birth) to maximum 15.3% level (14-days old), while the rars fed FO diet showed 78-79% of CO group throughout the period. Rats fed FO diet showed higher incorparation of DHA from 15.2% at birth to a maximum level of 18.5% at 140days, while the rats fed CO diet showed only 7.0% incorporation of DHA at birth and a maximum level of 11.1% at 21-days. Compared to CO group, FO group showed lower ratio of chol/PL and higher content of DHA in brain microsomal membrane, resulting in better membrane fluidity. Total amount of DNA per gram of brain was reached maximum level at 21 days in both groups. This would be a period of the cell proliferation during brain development. Overall, the rats fed fish oil diet showed a higher incorporation of DHA and membrane fluidity in the brain and better learning performances (p<0.05).