Trends In Sex Ratio Research Articles

Trend of sex ratio at birth in a public hospital in Hong Kong from 2001 to 2010

To identify factors affecting the sex ratio at birth. Cross-sectional study. Obstetric department of a public hospital in Hong Kong. All pregnant women delivered between 2001 and 2010. Sex ratio at birth versus women's eligibility status, age, parity, number of miscarriages or terminations of pregnancy, and number of fetuses were analysed using the Chi squared test. Multivariate regression was used to determine the effects of multiple factors on the sex of the newborn. A total of 54 039 cases were reviewed. The sex ratio at birth changed since 2003, and became unbalanced (>107 males per 100 females) since 2006 revealed by a significant increase in males per 100 females, from 106.6 in 2001-2005 to 111.4 in 2006-2010. From 2001 to 2010, the sex ratio at birth increased from being balanced to becoming unbalanced in eligible persons, and became more unbalanced in non-eligible persons. The ratio increased in eligible persons after having two children, but in non-eligible persons after having one child. The sex ratio at birth was unbalanced (1.095) in singleton pregnancies, but balanced (1.019) in multiple pregnancies. Based on logistic regression, the chance of a male baby being born increased with parity of 2 or above (odds ratio=1.1; P<0.001), non-eligible person status (odds ratio=1.05; P=0.034), and delivery in the period 2006-2010 (odds ratio=1.04; P=0.019). The ratio was not increased with advanced maternal age, the number of miscarriages/terminations of pregnancy, and number of fetuses. Compared with 2001-2005, the sex ratio at birth became unbalanced in 2006-2010. An unbalanced ratio ensued in the latter period in both eligible and non-eligible persons, but to a greater extent and even after having one child in the latter group.

Silver eel (Anguilla anguilla) population dynamics and production in the River Shannon, Ireland

AbstractThe European eel (Anguilla anguilla) is in decline throughout its distribution and accurate regional information, particularly on the silver eel life‐stage, is an essential component of stock recovery plans. Therefore, silver eel population dynamics and production were investigated on the Irish River Shannon. Size frequency analysis during the annual seaward migration showed that between 2008 and 2011, seasonal trends in both sex ratio and female size occurred. Catch analysis and mark‐recapture experiments were undertaken during the same period to determine silver eel production. Due to extreme discharge in 2009, no catch data was available for 17 nights, and a novel protocol was developed using a Dual Frequency Identification Sonar (DIDSON) to quantify silver eel migration. In 2008, silver eel production was estimated at 57.3 t (1.35 kg·ha−1), but an additional 18.3 t of potential migrants were estimated to have been removed by the summer yellow eel fishery. In 2009, following closure of the yellow eel fishery, silver eel production increased to 68.6 t (1.62 kg·ha−1), before declining to 62.7 t (1.47 kg·ha−1) in 2010 and 61.6 t (1.45 kg·ha−1) in 2011. Modelling, based on long‐term stocking data (1959–2011) and retrospectively estimated silver eel production (1992–2007) suggests that despite commercial fishery closure on the river, the decline in River Shannon silver eel production will continue for at least the coming decade.

Ten year trend of sex ratio at birth in a public hospital of an Indian state with known skewed sex ratio

Ten year trend of sex ratio at birth in a public hospital of an Indian state with known skewed sex ratio

Human sex ratio at amniocentesis and at birth in Taiwan

ObjectivesAn increase in the proportion of male-to-female live births has raised concerns in Taiwan. Disclosure of fetal sex during prenatal screening is not allowed by the Taiwan government. Fetal sex annotation in clinical genetic reports is also prohibited. This study tested the hypothesis that the male-to-female sex ratio at amniocentesis should be lower than the sex ratio at birth, if a certain percentage of female fetuses are being selectively aborted after amniocentesis. Therefore, we examined the differences between fetal sex ratio at amniocentesis at a tertiary medical center in southern Taiwan and the nationwide sex ratio at birth in Taiwan from 1992 to 2011. Materials and MethodsData of normal male and female karyotypes during the study period were collected from the cytogenetic laboratory of the National Cheng Kung University Hospital (NCKUH) in southern Taiwan. Data of sex ratio at birth nationwide in Taiwan were obtained from the Department of Statistics, Ministry of the Interior, Taiwan. We calculated 95% binominal confidence intervals for the sex ratios and differences between fetal sex ratio at amniocentesis, and nationwide sex ratio at birth were tested by the χ2 test and Bonferroni correction. ResultsThe nationwide sex ratio at birth ranged from 1.07 to 1.11 during the period from 1992 to 2011 in Taiwan, with the highest in 2004 and the lowest in 1993. The fetal sex ratio at amniocentesis at NCKUH ranged more widely (0.82–1.28), with the lowest in 1993 and the highest in 2007. After regression analysis, both trends of sex ratio at amniocentesis during midtrimester and at birth were not significantly increased by years. Furthermore, the sex distribution at amniocentesis during midtrimester did not differ significantly from the nationwide sex ratio at birth (1.113 vs. 1.092, p = 0.151). ConclusionsThe results showed that sex ratio was already skewed toward male at midtrimester. Our data imply that artificial sex selection, if it were present, might have already emerged prior to the timing of amniocentesis. However, more large nationwide studies on sex ratios in Taiwan are warranted.

Geographical Variations in Sex Ratio Trends over Time in Multiple Sclerosis

BackgroundA female/male (F/M) ratio increase over time in multiple sclerosis (MS) patients was demonstrated in many countries around the world. So far, a direct comparison of sex ratio time-trends among MS populations from different geographical areas was not carried out.ObjectiveIn this paper we assessed and compared sex ratio trends, over a 60-year span, in MS populations belonging to different latitudinal areas.MethodsData of a cohort of 15,996 (F = 11,290; M = 4,706) definite MS with birth years ranging from 1930 to 1989 were extracted from the international MSBase registry and the New Zealand MS database. Gender ratios were calculated by six decades based on year of birth and were adjusted for the F/M born-alive ratio derived from the respective national registries of births.ResultsAdjusted sex ratios showed a significant increase from the first to the last decade in the whole MS sample (from 2.35 to 2.73; p = 0.03) and in the subgroups belonging to the areas between 83° N and 45° N (from 1.93 to 4.55; p<0.0001) and between 45° N to 35° N (from 1.46 to 2.30; p<0.05) latitude, while a sex ratio stability over time was found in the subgroup from areas between 12° S and 55° S latitude. The sex ratio increase mainly affected relapsing-remitting (RR) MS.ConclusionsOur results confirm a general sex ratio increase over time in RRMS and also demonstrate a latitudinal gradient of this increase. These findings add useful information for planning case-control studies aimed to explore sex-related factors responsible for MS development.

DAUGHTER DISCRIMINATION AND FUTURE SEX RATIO AT BIRTH IN INDIA

This paper examines recent trends in sex ratio at birth in all the major states of India, based on three rounds of the National Family Health Survey. It finds evidence of an increase in the ratio, particularly at the second-order birth among women having a first daughter in many states in the northwestern region of the country. Also, there are signs of daughter aversion emerging in Odisha, an eastern state. Based on parity progression ratios and the trend in sex selection, an attempt is made to estimate the peak of sex ratio at birth in India. With moderate intensification in sex selection in the northwestern region, sex ratio at birth is expected to reach a peak of 117–119 males per 100 females around the period 2021–2026. If, in addition, sex selection spreads further in the southeastern region, the sex ratio at birth in India could even increase to a level of 124.

Trends in Clinical, Demographic, and Biochemical Characteristics of Patients With Acute Myocardial Infarction From 2003 to 2008: A Report From the American Heart Association Get With The Guidelines Coronary Artery Disease Program

BackgroundAn analysis of the changes in the clinical and demographic characteristics of patients with acute myocardial infarction could identify successes and failures of risk factor identification and treatment of patients at increased risk for cardiovascular events.Methods and ResultsWe reviewed data collected from 138 122 patients with acute myocardial infarction admitted from 2003 to 2008 to hospitals participating in the American Heart Association Get With The Guidelines Coronary Artery Disease program. Clinical, demographic, and laboratory characteristics were analyzed for each year stratified on the electrocardiogram at presentation. Patients with non–ST-segment–elevation myocardial infarction were older, more likely to be women, and more likely to have hypertension, diabetes mellitus, and a history of past cardiovascular disease than were patients with ST-elevation myocardial infarction. In the overall patient sample, significant trends were observed of an increase over time in the proportions of non–ST-segment–elevation myocardial infarction, patient age of 45 to 65 years, obesity, and female sex. The prevalence of diabetes mellitus decreased over time, whereas the prevalences of hypertension and smoking were substantial and unchanging. The prevalence of “low” high-density lipoprotein increased over time, whereas that of “high” low-density lipoprotein decreased. Stratum-specific univariate analysis revealed quantitative and qualitative differences between strata in time trends for numerous demographic, clinical, and biochemical measures. On multivariable analysis, there was concordance between strata with regard to the increase in prevalence of patients 45 to 65 years of age, obesity, and “low” high-density lipoprotein and the decrease in prevalence of “high” low-density lipoprotein. However, changes in trends in age distribution, sex ratio, and prevalence of smokers and the magnitude of change in diabetes mellitus prevalence differed between strata.ConclusionsThere were notable differences in risk factors and patient characteristics among patients with ST-elevation myocardial infarction and those with non–ST-segment–elevation myocardial infarction. The increasing prevalence of dysmetabolic markers in a growing proportion of patients with acute myocardial infarction suggests further opportunities for risk factor modification. (J Am Heart Assoc. 2012;1:e001206 doi: 10.1161/JAHA.112.001206.)

Does famine influence sex ratio at birth? Evidence from the 1959–1961 Great Leap Forward Famine in China

The current study examined the long-term trend in sex ratio at birth between 1929 and 1982 using retrospective birth histories of 310 101 Chinese women collected in a large, nationally representative sample survey in 1982. The study identified an abrupt decline in sex ratio at birth between April 1960, over a year after the Great Leap Forward Famine began, and October 1963, approximately 2 years after the famine ended, followed by a compensatory rise between October 1963 and July 1965. These findings support the adaptive sex ratio adjustment hypothesis that mothers in good condition are more likely to give birth to sons, whereas mothers in poor condition are more likely to give birth to daughters. In addition, these findings help explain the lack of consistent evidence reported by earlier studies based on the 1944-1945 Dutch Hunger Winter or the 1942 Leningrad Siege.

Can leftovers from predators be reliably used to monitor marine turtle hatchling sex-ratios? The implications of prey selection by ghost crabs

In marine turtles, the sex of an individual is determined by temperatures experienced during embryonic development. Gonad histological observation is still the only reliable way to determine hatchling sex, hampering the study of reproduction and of the demographic conse- quences of context-dependent sex-ratios, a subject of interest in a warming planet. We investigated whether hatchling remains from predation by Ocypode cursor can be used to estimate sex-ratio trends in a green turtle rookery at Poilao, Guinea-Bissau (1052 0 N, 1543 0 W). Sex could be readily determined in 77 and 79% of the predated hatchlings in 2008 and 2009, respectively. By comparing hatchlings killed by crabs, hatchlings accidentally dying on the reefs, and live hatchlings, we show that ghost crabs select the smaller prey, but do not select according to hatchling sex, which is explained by the lack of hatchling size dimorphism in this population. The proportion of male hatchlings was 0.45 ± 0.06 and 0.15 ± 0.06 for early and late-season clutches, respectively, these differences most likely being explained by rainfall. Using leftovers from predation by crabs may be a good solution to non-inva- sively monitor broad trends in sex-ratios of sea turtles.

Trends in selective abortions of girls in India: analysis of nationally representative birth histories from 1990 to 2005 and census data from 1991 to 2011

India's 2011 census revealed a growing imbalance between the numbers of girls and boys aged 0-6 years, which we postulate is due to increased prenatal sex determination with subsequent selective abortion of female fetuses. We aimed to establish the trends in sex ratio by birth order from 1990 to 2005 with three nationally representative surveys and to quantify the totals of selective abortions of girls with census cohort data.We assessed sex ratios by birth order in 0·25 million births in three rounds of the nationally representative National Family Health Survey covering the period from 1990 to 2005. We estimated totals of selective abortion of girls by assessing the birth cohorts of children aged 0-6 years in the 1991, 2001, and 2011 censuses. Our main statistic was the conditional sex ratio of second-order births after a firstborn girl and we used 3-year rolling weighted averages to test for trends, with differences between trends compared by linear regression.The conditional sex ratio for second-order births when the firstborn was a girl fell from 906 per 1000 boys (99% CI 798-1013) in 1990 to 836 (733-939) in 2005; an annual decline of 0·52% (p for trend=0·002). Declines were much greater in mothers with 10 or more years of education than in mothers with no education, and in wealthier households compared with poorer households. By contrast, we did not detect any significant declines in the sex ratio for second-order births if the firstborn was a boy, or for firstborns. Between the 2001 and 2011 censuses, more than twice the number of Indian districts (local administrative areas) showed declines in the child sex ratio as districts with no change or increases. After adjusting for excess mortality rates in girls, our estimates of number of selective abortions of girls rose from 0-2·0 million in the 1980s, to 1·2-4·1 million in the 1990s, and to 3·1-6·0 million in the 2000s. Each 1% decline in child sex ratio at ages 0-6 years implied 1·2-3·6 million more selective abortions of girls. Selective abortions of girls totalled about 4·2-12·1 million from 1980-2010, with a greater rate of increase in the 1990s than in the 2000s.Selective abortion of girls, especially for pregnancies after a firstborn girl, has increased substantially in India. Most of India's population now live in states where selective abortion of girls is common.US National Institutes of Health, Canadian Institute of Health Research, International Development Research Centre, and Li Ka Shing Knowledge Institute.

Modeling Prenatal Son Preference: Some New Perspectives from China

China has since the mid-1980s witnessed an increasing trend in sex ratio at birth (SRB) imbalance. While the literature agrees that SRB is caused by parents' need to have a son, it is not clear if an increase in SRB reflects an increase in son preference. This study aims at bridging this gap by developing a model to estimate prenatal son preference based on SRB and total fertility rates (TFR). Data on SRB and TFR from China are applied to the model. The results show that since the mid-1980s, prenatal son preference has fluctuated, and trends in SRB and prenatal son preference by province and by rural, township and urban areas sometimes diverge. In order to interpret these results, changing trends in prenatal son preference is discussed in relation to social change in China. The study draws conclusions at two levels. First of all, theoretically, it concludes that increased SRB does not have to signify increasing prenatal son preference when fertility rates fall. Secondly, it concludes that in China, the process of socioeconomic development has diverging impact on son preference, weakening it in some instances, while reinforcing it in others. Modeling son preference as suggested is useful for posing relevant questions with regard to how and why son preference changes. It also has important implications for where, if and how interventions that address skewed SRB should be planned.

Sex allocation in Savi’s warblers Locustella luscinioides: multiple factors affect seasonal trends in brood sex ratios

Sex allocation theory predicts that whenever the relative fitness of sons and daughters differ, females should invest more in the sex with the greatest fitness return. In this study, we evaluated the influence of various ecological factors on the brood sex ratio (BSR) of Savi’s warblers (Locustella luscinioides) across several breeding seasons. There was a slight but significant female production bias at the population level, which is consistent with the ‘local resource competition’ hypothesis, as the breeding density is very high and females are more prone to disperse. We found that there was a significant decline in BSR during the breeding season, but no influence of male size, female size, social status nor extra-pair paternity were detected. The seasonal decline in BSR was further evaluated by assessing the within- and between-female effects, which indicated that multiple factors were operating simultaneously in our study population. First, there was a significant within-female decline in BSR, which was consistent with the decline in female condition due to the reproductive effort associated with multiple brooding (supporting the Trivers and Willard hypothesis). Second, a significant decline in BSR with the laying date of first clutches of different pairs indicated that male and/or female qualities are also associated with the seasonal variation in BSR. Finally, a comparison between the sex of the youngest nestling with the remaining ones did not suggest any bias, indicating that females do not compensate for the increased mortality of the last nestling (caused by asynchronous hatching) by producing a male from the last laid egg.

A cross-sectional study of factors influencing sex preference of a child among married women in reproductive age group in a rural area of Pune, Maharashtra

Sir, Sex ratio is an important social indicator to measure the extent of prevailing equity between males and females in the society. It is also a sensitive indicator of development. According to 2001 census, India recorded a sex ratio of 933 females per 1000 males,(1)which is lowest among the ten most populous countries of the world. The preference for son and discrimination against the girl child is almost universal in India and manifest it in many ways. In Maharashtra, the sex ratio has declined from 934 females per 1000 males in 1991 to 922 females in 2001 and the sex ratio for the 0-6 years age group, known as child sex ratio, which is a powerful indicator of social health of any society has also shown a sharp decline from 946 in 1991 to 917 in 2001.(1)According to 2001 census, Pune district has a child sex ratio of 906 which was 943 according to 1991 census. Owing to declining trend in child sex ratio, a community-based, cross- sectional study was carried out in the rural field practice area of one of the medical college in Pune, among married women in reproductive age group of 15-45 years to determine factors influencing sex preference of a child. Total 210 married women in reproductive age group were selected for the study. Widow, separated and divorcee women were excluded from the study. Simple random sampling technique was used for collection of data. The study subjects were interviewed with structured and pre-tested questionnaire. Mean age of study subjects was 26.75 years. 77.14% of the study subjects were Hindus. 17.5% of the study subjects were illiterate while only 3.81% study subjects were studied up to graduation. 37.62% study subjects were educated up to high school. 90.48% study subjects were housewives, while 5.71% were laborers. 2.86% study subjects had own business and only 2 were employed. Socio-economic status according to modified B. G. Prasad classification showed that majority of the study subjects belonged to class III (33.8%) followed by class IV (31.9%). Mean age at marriage was 18.47 years. The most common reason of son preference was support at old age (57.14%) followed by demand for male child by other family members and community (32.88%). Study by Jai Rup Singh and Centre for Research on Environment Health and Population Activities, Katmandu, Nepal also observed similar reasons for preference to male child.(2,3)The person who had male child will go to heaven (30%) after death was one of the beliefs among study subjects, which was also one of the important reason for preference for the male child. The most common reason for preference to girl child was like for girl child (62.38%). There was no association found between literacy status and socio-economic class of the study subjects and preference to male child in the present study. 22 (10.47%) among 210 subjects had gone for sex determination during their pregnancy for male child. Study showed highly significant association between literacy status and sex determination during pregnancy (χ2value=21.55, P value 0.05). A UN Convention to Review Status of Women” at UN headquarters, New York by Patel Vibhuti also stated that decline in sex ratio is associated with the increase in female literacy rate.(4)One of the important findings of the study was that 103 (49.04%) of the study subjects had given the history of teen-age pregnancy. Recent National Family Health Survey-3 also shown that 30% women underwent teen-age preganacies.(5)The issue of teen-age pregancy needs attention and further research is required to explore this issue. In conclusion, the present study has shown that there is a preference for male child in the community. To improve the declining child-sex ratio, it is essential to promote a positive image of the girl child and to value and celebrate the girl child’s life in our family and community.

Sex ratio patterns in population estimates

The mid-year estimates (MYEs) resulting from the 2001 Census have a sex ratio pattern differing from patterns in previous estimates. Research has been undertaken to explain the observed sex ratio pattern in England and Wales (EW), covering recent censuses and population estimates during the current intercensal period. The aims of this paper are to present some of the research explaining this sex ratio pattern and, secondly, suggest ways to prepare for the 2011 Census and beyond. A number of approaches have been taken to understand the drivers of the sex ratio pattern and provide evidence on plausibility. The Patient Register Data (PRD) was examined as a potential comparator. Sex ratios in other countries were compared with the EW sex ratio patterns. An accounting exercise for different explanatory scenarios around the remaining unexplained difference between estimates and 2001 Census was undertaken. Finally, demographic analyses examine trends in sex ratios among the migrant stock of the EW and foreign born populations to put into context the sex ratios in MYEs following the 2001 Census.

Sexual segregation of common minke whales (Balaenoptera acutorostrata) in Greenland, and the influence of sea temperature on the sex ratio of catches

Abstract Laidre, K. L., Heagerty, P. J., Heide-Jørgensen, M. P., Witting, L., and Simon, M. 2009. Sexual segregation of common minke whales (Balaenoptera acutorostrata) in Greenland, and the influence of sea temperature on the sex ratio of catches. – ICES Journal of Marine Science, 66: 2253–2266. The harvest of common minke whales (Balaenoptera acutorostrata) in West Greenland has historically been skewed towards female whales, yet a complete analysis of spatial and temporal patterns of catch sex ratio has never been conducted. We examined trends in the sex ratio of catches over time, season, space, and relative to sea temperature using 2400 records from inshore Greenland subsistence whaling operations (1960–2006) and 2072 records from offshore Norwegian commercial operations (1968–1985). Logistic regression models were developed to examine the trend in sex ratio in three regions (Northwest, NW; Central West, CW; Southwest, SW) and by latitude. The highly skewed proportion of females in all catches was strongly positively correlated (r2 = 0.8) with latitude in the offshore catches (&gt;100 km). Generalized linear models of inshore catches indicated slightly increasing though non-significant trends in the proportion of females taken off CW and NW Greenland and a significant declining trend off SW Greenland. Sensitivity analyses show that the declining inshore SW trend was entirely accounted for by the past 5 years (2002–2006) of data. Models containing both year and temperature interactions suggested that either parameter provided an equivalent explanation of the variation in trends across regions.

Interdependence of social structure and demography in the southern elephant seal colony of Península Valdés, Argentina

AbstractSouthern elephant seals breed at Península Valdés (PV, Argentina) along 200 km of coastline. Annual pup counts at peak breeding season for the entire colony increased from 12,113 in 1995 to 14,350 in 2006. Two demographic subunits were identified in the North and South of PV with different trends in births numbers, sex ratios and harem sizes. Birth numbers increased in the South, but decreased sharply in the North. To explain the trends in the colony and subunits, a population model was proposed that integrates social structure (harem size and sex ratio) in a fertility function that quantifies the effects of the social structure on the number of births. We found that a better fit to census data results from our model compared to a linear one (χ12= 4.027, P= 0.045). The model was then used to test alternative hypotheses about the role of recruitment and migration on the dynamic of the two subunits. Results indicated the relevance of considering social structure in population models of gregarious and polygynous species, and is an additional tool for comparative studies between populations of elephant seals where long term census are available.

Neither Biased Sex Ratio nor Spatial Segregation of the Sexes in the Subtropical Dioecious Tree Eurycorymbus cavaleriei (Sapindaceae)

Knowledge of sex ratio and spatial distribution of males and females of dioecious species is both of evolutionary interest and of crucial importance for biological conservation. Eurycorymbus cavaleriei, the only species in the genus Eurycorymbus (Sapindaceae), is a dioecious tree endemic to subtropical montane forest in South China. Sex ratios were investigated in 15 natural populations for the two defined ages (young and old). Spatial distribution of males and females was further studied in six large populations occurring in different habitats (fragmented and continuous). The study revealed a slight trend of male-biased sex ratio in both ages of E. cavaleriei, but sex ratio of most populations (13 out of 15) did not display statistically significant deviation from equality. All of the four significantly male-biased populations in the young class shifted to equality or even female-biased. The Ripley's K analysis of the distribution of males with respect to females suggested that individuals of the opposite sexes were more randomly distributed rather than spatially structured. These results suggest that the male-biased sex ratio in E. cavaleriei may result from the precocity of males and habitat heterogeneity. The sex ratio and the sex spatial distribution pattern are unlikely to constitute a serious threat to the survival of the species.

Variable susceptibility and response to estrogenic chemicals in Menidia menidia

Environmental endocrine disruptors can profoundly impact sex ratios of fish popula- tions, especially if the fish exhibits plasticity in sex determination. The Atlantic silverside Menidia menidia exhibits a genetically based latitudinal cline in numerous traits including temperature- dependent sex determination (TSD), which varies from high thermal influence on sex determination in southern fish, to pure genetic sex determination (GSD), with no thermal influence in northern fish. We used this gradient in TSD/GSD to test for differential population susceptibility to a common municipal wastewater constituent, 17 β-estradiol (E2), among 4 populations with varying levels of TSD. Larvae were exposed to E2 during sex differentiation and assessed for sex ratios. The sex ratio in southern populations was more responsive to E2 than in northern populations, indicating differen- tial population sensitivity. To assess the potential sensitivity of wild populations to estrogenic com- pounds, we measured the sex ratio in 12 M. menidia populations over a 3 yr period along a pro- nounced longitudinal gradient in sewage effluent and urbanization across Long Island. Water temperatures were measured to account for thermal influence on sex ratio. We found a significant trend toward female-biased sex ratios in more urbanized estuaries, with lower proportions of females in less impacted estuaries. Temperature was ruled out as the primary cause. Because sewage efflu- ent often carries high concentrations of estrogenic compounds, and our experiments confirmed a heightened sensitivity to E2 in fish with TSD, the most likely reason for the longitudinal trend in sex ratio is a gradient in the concentration of estrogenic compounds associated with urbanization.

Trends in Sex Ratio at Birth according to Parental Social Positions: Results from Vital Statistics Birth, 1981-2004 in Korea

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. 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). 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. 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.

Hundred Years of Juvenile Masculinity in India: Why the Contemporary Pattern is Important?

Since the beginning of the last century, sex ratio (male to female) in India is showing disturbing patterns with relatively fewer numbers of females compared to males. The magnitude of juvenile masculinity has increased since 1980s with no sign of reverse. The time trend of juvenile sex ratio brings out demographic transition type ‘sex ratio transition’ in Indian population. Using data from the last hundred years, the paper tries to figure out the pattern of sex ratio transition at all India as well as at the state level. Spatial pattern of juvenile sex ratio have been judged and contemporary increase in masculinity have been highlighted. Despite the common wisdom that juvenile sex ratio in India is rising since the last century, the present paper indicates that juvenile masculinity is a long-standing problem of India that gets momentum during the recent period due to demographic as well as socio-economic forces.