• YAKHAK HOEJI
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• v.45 no.2
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• pp.190-204
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• 2001

This study was conducted to investigate for its effects on reproductive and developmental toxicity of recombinant human epidermal growth factor (rhEGF) in Sprague-Dawley rats. Male rats were administered rhEGF at doses of 1, 10, 100, and 1000$\mu$g/kg/day, respective1y, by subcutaneous injection from 63 days before and throughout to mating period until the day before sacrifice. Female rats were administered rhEGF at the same doses from 14 days before mating to day 20 of gestation or to day 21 of lactation. We examined the male and female fertility indices and maternal toxicity of F0 parental animals. Also, we examined the external, visceral, or skeletal malformation of fetuses, growth and development, behavior, and/or reproductive performance of F1 animals. At the highest dose (1,000 $\mu$g/kg), the mean body weights of F0 animals were significantly increased in males and females at 3 or 2 weeks after treatment, respective1y. No clinical signs and food intakes were observed at any time during the experimental period by rhEGF treatment. In autopsy examination, the relative and absolute liver weights significantly increased in both sexes of 1,000 $\mu$g/kg. At the highest dose (1,000 $\mu$g/kg), there was a statistically significant increase of pregnancy period and the number of dead fetuses. Moreover, significant increase of mean fetal body weight and decrease of number of live fetuses, which related to the difficult dilivery were observed in highest dose group. In Fl examination, no adverse effects on external, visceral, and skeletal malformation, physical and functional development, behavior or reproductive ability of Fl animals were observed in any group. Also, there was no significant difference between control and treated groups in copulation or fertility indices of Fl animals. These results indicate that rhEGF had no adverse effect on fertility and reproductive ability of Sprague-Dawley rats.

• Journal of Families and Better Life
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• v.24 no.6 s.84
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• pp.177-193
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• 2006

This study analyzes marriage and fertility rates in Korea and makes recommendations for family policy. Based on the 'The Report of Marriage & Divorce Statistics in 2005' and data from the Korea Statistical Information System (KOSIS) of the National Statistics Organization, the trends, reasons for marriage rates changes, and future expectations were critically reviewed. In addition, the relationship between marriage and fertility rates was analyzed. The principle characteristics of marriage rates are as follows: 1) the M-shape of the longitudinal crude marriage rates; 2) the increased age of individuals entering their the first marriage; 3) the increase in remarriage rates; 4) the changes in the patterns of remarriage; 5) the increased in the age at which individuals remarry and; 6) the increase in marriage to non-Koreans. The marriage and fertility rates changes are a permanent normative shift because of 1) later marriage because of women's increased education and labor force participation 2) rational choices about birth control 3) reduced population because of the aging of baby boomers 4) structural changes in the marriage market and 5) egalitarian changes in women's attitudes toward marriage and family. The recommendations for future family policy were as follows: 1) the need for a realistic, long-term family policy because the current marriage patterns will continue; 2) the need to develop new statistics such as fertility rates that are based on marriage cohort or birth cohort because family behavior is a mixture of personal, social and political responses; 3) the need for impact analysis of current family policy about increasing fertility rates; 4) the need for a new family perspective that encompasses diverse marriage and family patterns; 5) the need to focus on men's role in families because of women's changing roles and family interaction patterns and; 6) the need for preventive family policies such as family life education.

• Clinical and Experimental Reproductive Medicine
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• v.48 no.3
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• pp.203-210
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• 2021

We performed a systematic review and meta-analysis to evaluate whether intralipid administration improved the outcomes of in vitro fertilization. Online databases (PubMed, Cochrane Library, Medline, and Embase) were searched until March 2020. Only randomized controlled trials (RCTs) that assessed the role of intralipid administration during in vitro fertilization were considered. We analyzed the rates of clinical pregnancy and live birth as primary outcomes. Secondary outcomes included the rates of chemical pregnancy, ongoing pregnancy, and missed abortion. We reviewed and assessed the eligibility of 180 studies. Five RCTs including 840 patients (3 RCTs: women with repeated implantation failure, 1 RCT: women with recurrent spontaneous abortion, 1 RCT: women who had experienced implantation failure more than once) met the selection criteria. When compared with the control group, intralipid administration significantly improved the clinical pregnancy rate (risk ratio [RR], 1.48; 95% confidence interval [CI], 1.23-1.79), ongoing pregnancy rate (RR, 1.82; 95% CI, 1.31-2.53), and live birth rate (RR, 1.85; 95% CI, 1.44-2.38). However, intralipid administration had no beneficial effect on the miscarriage rate (RR, 0.75; 95% CI, 0.48-1.17). A funnel plot analysis revealed no publication bias. Our findings suggest that intralipid administration may benefit women undergoing in vitro fertilization, especially those who have experienced repeated implantation failure or recurrent spontaneous abortion. However, larger, well-designed studies are needed to confirm these findings.

• Journal of applied mathematics & informatics
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• v.24 no.1_2
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• pp.49-64
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• 2007

In this paper, we investigate optimal policies for three age-dependent populations in a competition system, which is controlled by fertility. By using Dubovitskii-Milyutin's general theory, the maximum principles are obtained for problems with free terminal states, infinite horizon and target sets, respectively.

• Development and Reproduction
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• v.15 no.1
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• pp.61-69
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• 2011

Previously, we have shown that Bcl2l10 as a member of Bcl-2 family, key regulators of the apoptotic process, is dominantly expressed in oocytes of ovary but several member of the Bcl-2 family are not expressed in oocytes. Recent our studies had been processed about roles and regulatory mechanisms of Bcl2l10 in oocytes. Microinjection of Bcl2l10 RNAi into the cytoplasm of germinal vesicle oocytes resulted in metaphase I (MI) arrest and exhibited abnormalities in their spindles and chromosome configurations (Yoon et al., 2009). The present study was conducted to elucidate the downstream genes regulated by Bcl2l10 and signaling networks in Bcl2l10 RNAi microinjected oocytes by using microarray analysis. Surprisingly, we found that a large proportion of genes regulated by Bcl2l10 RNAi were involved in the cell cycle and actin skeletal system regulation as important upstream genes of Bcl2l10. Among the transcripts with highly significant fold changes more than 2-fold, Tpx2 and Cep192 are 16.1- and 8.2-fold down regulated respectively by Bcl2l10 RNAi. Tpx2 and Cep192 are known as cofactors that control Aurora A kinase activity and localization. Therefore, we concluded that Bcl2l10 may have important roles during oocyte meiosis as functional upstream regulator of Tpx2 and Cep192.

• KDI Journal of Economic Policy
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• v.31 no.1
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• pp.105-138
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• 2009

Although the decline in fertility rate is generally observed along the history of economic development throughout the world, the continuing decline hitting below the replacement level in Korea over the recent years gathered serious social concerns on the ground that it accelerates the process of population aging. The total fertility rate in Koreareached 2.08 in 1983, and gradually fell to the levels of 1.08 in 2005 and 1.26 in 2007. The policy debate over the role of the government has been focused mainly on the level of theoretical discussion without substantial basis on firm empirical evidence and the determinants of fertility. The objective of the paper is to empirically investigate the fertility effect of the female wage, which is understood as one of the most important determinants of fertility in Koreasince 1980 focusing on one aspect of fertility, namely birth spacing. Using the Korean National Fertility Survey conducted in 2006, I estimate a duration model of first and second births taking into account individual heterogeneity, which turned out to be an important factor to control for. Compared with previous studies in the literature on the Korean fertility, the study has an advantage of using the complete pregnancy history of women in a more representative sample. Unlike the previous studies, the analysis also deals with the endogeneity of marriage by treating a certain age, rather than age at marriage, as the time in which a woman becomes exposed to the risk of pregnancy. The study shares the common problem in the literature on birth spacing of lacking relevant wage information for respondents in a retrospective survey. I estimate the wage series as a function of the basic characteristics using the annual Wage Structure Survey from 1980 to 2005, which is considered as a nationally representative sample for wage information of employees. The results suggest that the increase in female wage by 10 percent leads to a decrease in second birth hazard by 0.56~0.92 percentage points and that the increase in spouse's wage by the equal amount is accompanied by the increase in second birth hazard by 0.36~1.13 percentage points. These estimates are more precisely estimated and of smaller magnitude than those presented by the previous studies. The results are robust to the different specifications of the wage equation. The simulation analysis based on the predicted values shows that about 17% of the change in the second birth hazard over the period 1980 to 2005 was due to the change in the female wage. Although there is some limitation in data, the results can be viewed as one estimate of the role of female wage on the recent fertility decline in Korea. The question raised by the paper is not a normative one of whether a government should promote childbearing but a positive one thatexplains fertility decline. Therefore, if there is a wide consensus on promoting childbearing, the finding suggests that the policies designed to reduce the opportunity cost of women in the labor market would be effective. The recent movement of implementing a wide range of family-friendly policies including child care support, maternity leave, parental leave and tax benefit in developed countries should be understood in this context.

• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.369-374
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• 1999

One hundred forty cows that have claw disorder have been used to study the association between lameness and reproductive disorders. Weak estrus owing to ovarian hypoplasia (41.4%) followed by follicular cyst (39.3%) was more frequent than any other disorders. Two hundred ninety-four cows have been used to study the association between lameness and calving to first service and calving to conception intervals depending on lactations, claw disease and floor conditions. And a comparison of number of services per conception between cows with lameness and cows free from lameness was carried out. The calving to first service intervals were significantly increased from average 78 to 102.5 days and calving to conception intervals were significantly increased from 109.6 to 150.6 days in cows with lameness. The calving to first service and calving to conception intervals were not significant different between lactations in cows with lameness. In comparison of calving to first service and calving to conception intervals in cows with lameness depending on claw disease and floor conditions, there was no significant difference. The average number of services per conception was increased from 1.73 to 2.57 in cows with lameness. Service numbers were more frequent during second lactation (3.0 services) but there was no significant difference between lactations in cows with lameness. Therefore, it is likely that the management of lameness is important factor on proper health control of cows and the cows with lameness show decreased fertility.

• Korean journal of applied entomology
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• v.36 no.3
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• pp.277-282
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• 1997

Chemosterilant effect of chlorpyrifos-methyl (CPM) on the beet armyworm, Spodoptera e.rigua (Hubner) was investigated, using topical application. Egg fecundity and fertility were analyzed in the adults reared from the fifth instar larvae which were treated with sublethal doses of CPM. Though CPM reduced fecundity a little, it gave significant negative effect on egg fertility in a dose-dependent manner. Genetic analysis was performed by reciprocal crosses between treated (100 Wgllarva) and untreated individuals and showed a dominant lethal effect of CPM on egg fecundity and fertility. This results indicate that chlorpyrifos-methyl may act as a chemosterilant as well as a well-known neurotoxicant, and suggest that it can be used in genetic control program.

• Korea journal of population studies
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• v.9 no.2
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• pp.42-52
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• 1986

An attempt had been made to obtain current information on induced abortion among currently married women aged 15 to 44. The source of data was 1985 National Fertility and Family Planning Survey conducted by Korea Institute for Population and Health in may 1985. 1. At the time of the survey, 53 percent of currently married women aged 15 to 44 had experienced induced abortion: 25.5 percent of the respondents who had experienced induced abortion only one time and another 27.6 percent more than two times. 2. The proportion of women who had experienced induced abortion seemed to increase according to the advance in age. It seemed that there was no significant difference in the experience rate of induced abortion by academic career, and there was inverse relationship between the experience rate of induced abortion and the age at first marriage. The experience rate if induced abortion by the number of living children was highest among those who had three children as 65.6 percent. 3. To analyze the effect of induced abortion on fertility, this study employed multiple regression analysis as a statistical technique. Instead of index representing fertility level the number of living children served as dependent variable. Independent variables used in analysis included age, age at first marriage, education level, ideal number of children, religion, frequency of induced abortion, total number of pregnancies and participation in labor force. Standardized partial regression coefficient of induced abortion was no less than -0.61. So, it can be concluded that induced abortion offered the great contribution on the birth control. A consistant health education and efficient management of family planning program would be essential for effectiveness of contraceptive practice.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.1
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• pp.35-39
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• 2019

This study aimed to recover the ovarian function through in vitro culture of preantral follicles from aged mice. First, we isolated the preantral follicles from ovaries of sixty-seven-week old B6D2F1 mice with decreased fecundity to know how many follicles were present in them, which was 6 preantral follicles including 2 primary, 2 early secondary and late secondary follicles from 8 aged mice. It was confirmed that a few follicles (~2) were present in aged mice through histological analysis compared to adult mice as control. The 9 days of in vitro culture of preantal follicles showed in vitro growth and induced maturation after treatment with hCG (2.5 IU/mL) and EGF (5 ng/mL). Cumulus cells in the cumulus-oocyte complexes (COCs) were removed using hyaluronidase and oocytes at the germinal vesicle (GV) and GV breakdown (GVBD) were obtained from preantral follicle culture of aged mice in vitro. In conclusion, these observations demonstrated that there still were a few preantral follicles in the ovaries of 67 week-old mice, which we were able to culture in vitro and oocytes were obtained from them. This study proposed an in vitro culture system using preantral follicle as a therapeutic strategy for fertility preservation in humans for assisted reproductive medicine.