Variation In Fertility Research Articles

Modelling age specific fertility rate in India through fertility curves

One of the important demographic features of any population is the fertility rate which has a direct relationship with both the social and the biological environment. Demographic factors like age at marriage, present family size, gender preference (Mahadevan [27], Bhasin [3], Asari and John [2], Chachra and Bhasin [18], Bhasin and Nag [19]) and socio economic factors like education, occupation, religion, contraceptive practice, etc. (Bhatia [20], Asari and John [2]) are the determinants of desired family size and all these are considered as the cause of the variation of fertility. So far researchers have proposed a variety of reproductivity measures and mathematical models to describe the reproductivity pattern of human population (Islam and Ali [21], Peristera and Kostaki [22] and Nasir et al. [23]). The objective of this study is to examine the current pattern of Age Specific Fertility Rate(ASFR) and to study the trend in fertile age groups by fitting non linear models to the ASFR data for all the states in India obtained from the sample registration system [1], of India. Cross Validity Prediction Power (CVPP), Shrinkage, and R2 are used to identify the best model for the states. Model identification for Forward Age Specific Fertility Rate (FASFR) and Backward Age Specific Fertility Rate (BASFR) along with validity measures are also presented in this paper.

Nutrient dynamics in paddy soil under rice culture mesocosm studies

The objectives of this study were to determine the nutrient losses through the soil columns with the variation of soil and fertilizer. The experiment was conducted in a net house of Sher-e-BanglaAgriculturalUniversity, Dhaka, Bangladesh during July–November to study the effect of fertilizer and manure on the growth and yield of T. aman rice and leaching loss of nutrients through undisturbed soil columns. The experiment consists of 2 factors i.e. soils and fertilizer plus manure. Two soils (S1= SAU Soil and S2= Sonargaon Soil) with 4 levels of fertilization, as F0: Control, F1: 100% N120P20K45S20 (FRG 2012), F2: 50% NPKS + 5 t/ha cowdung, F3: 50% NPKS + 2.1 t/ha poultry manure were used in the experiment. T. Aman (BR11) rice was grown in the soil cores. Altogether, there were 8 treatment combinations and the treatment combinations were replicated 3 times. Twenty four undisturbed soil cores collected in PVC pipes were placed at the bottom of the perforated plastic containers and two holes of each plastic container were connected to a conical flask that was used to collect column leachate. Leachates were collected at 25, 35, 45, 55, 65 and 75 DAT (Days after transplanting) and analyzed for N, P, K and S. The leachate N, P, K and S concentration varied with different soil, fertilizer and time. The higher N and S concentrations were found in the leachate of SAU soil and higher leachate K concentrations were obtained in Sonargaon soil. The higher amounts of N leaching were observed during 45–55 DAT and higher leachate N concentrations were found in F1 treatment. Higher leachate K concentrations were found in 100% chemical fertilizer treatment and higher leachate K concentrations were found at 35DAT in all fertilizer treatments. The leachate P concentration increased at 35 DAT and then decreased. Results revealed that soil had no significant effect on the yield and yield parameters. The yield contributing characters and yields were significantly affected by fertilizer and manure application. The highest effective tillers/core (17.0), plant height (105.6 cm), panicle length (23.70 cm), grain yield (0.046 kg/core) and straw yield (0.053 kg/core) of T. Aman rice were found from F1 (RDCF) treatment. The highest 1000-grain wt. (23.70 g) was obtained from F2 and filled grain/panicle (121.8) from T3 treatment and the lowest in F0 treatment. The highest grain yield was found by the application of recommended dose of chemical fertilizer which was statistically similar to F3 (50% NPKS + 2.1 ton poultry manure) treatment. The combined effects of soil and fertilizer were not significant but the highest grain (0.049 kg/core) and straw yields (0.056 kg/core) were recorded from S2F1 (Sonargaon Soil + 100% NPKS) treatment combination.J. Bangladesh Agril. Univ. 15(2): 199-205, December 2017

PERFORMANCE OF FERTILIZER METERING MECHANISMS OF PLANTERS AS A FUNCTION OF LONGITUDINAL INCLINATION

ABSTRACT: Sowing occurs in agricultural areas with irregular relief, influencing the quality of seed and fertilizer distribution. The aim of this study was to analyze the performance of different fertilizer metering mechanisms of planters as a function of longitudinal inclination. The experimental design was a completely randomized design with five treatments and six replications. Treatments consisted of five longitudinal inclinations to the metering mechanism (−10, −5, 0, 5, and 10 degrees). The mass of fertilizer collected per minute was considered as a replication. We worked with two types of fertilizers: a mixture of granules and powder. Metering mechanisms used were a horizontal toothed rotor, helical without flow restrictor, helical with lateral overflow, and helical with longitudinal overflow. The longitudinal inclination of ±10° in relation to the leveling altered the metered amount of both fertilizers used in all metering mechanisms. The helical with lateral overflow was the metering mechanism that obtained the smallest amount variation of fertilizer distributed in the different longitudinal inclinations, followed by the helical with longitudinal overflow, horizontal toothed rotor, and helical without flow restrictor.

Family Matters: Development of new family interrelationship variables for US IPUMS data projects.

In demographic datasets, researchers frequently want to identify how members of a household are related. In this paper, we develop a new method of estimating parental and spousal relationships using data on fertility patterns and family interrelationships. The improved method includes cohabiting and same-sex couples and is comparable across all modern US IPUMS data projects. A detailed variable indicates how the relationship was inferred and the level of ambiguity around that inference. The new IPUMS family interrelationship variables are very accurate, matching self-reported spouse/partner for 99.99% and parent for over 99.00% of respondents. Among those identified as same-sex couples, we match self-reported spouse/partner for 100% of respondents, 87.57% of whom self-identify as lesbian, gay, or bisexual. We further demonstrate that the new family interrelationship variables closely track temporal variation in teenage fertility.

Modelling Variation in Fertility Rates Using Geographically Weighted Regression

Australia is one of the largest countries in the world, and also one of the most urbanised. At the national level it can be characterised as a country with low fertility and high income per capita. However, there are significant geographic inequalities between different areas of the country in terms of fertility rates as well as education levels, income and employment opportunities. In this paper, we use birth registration and Census data to explore the spatial variation of fertility in Australia and how it relates to compositional and contextual characteristics of places. Geographically weighted regression allows us to analyse the spatial relationships and identify the geographical variability in the fertility experience of Australian women. We find substantial variation with some areas having a total fertility rate well above or below the national average. Around metropolitan areas much of the variation can be explained by differences in the socio-economic composition of the local population. However in more rural or remote parts of the country, understanding the variation in fertility is more difficult.

Variation in the benefits of multiple mating on female fertility in wild stalk-eyed flies.

Polyandry, female mating with multiple males, is widespread across many taxa and almost ubiquitous in insects. This conflicts with the traditional idea that females are constrained by their comparatively large investment in each offspring, and so should only need to mate once or a few times. Females may need to mate multiply to gain sufficient sperm supplies to maintain their fertility, especially in species in which male promiscuity results in division of their ejaculate among many females. Here, we take a novel approach, utilizing wild‐caught individuals to explore how natural variation among females and males influences fertility gains for females. We studied this in the Malaysian stalk‐eyed fly species Teleopsis dalmanni. After an additional mating, females benefit from greatly increased fertility (proportion fertile eggs). Gains from multiple mating are not uniform across females; they are greatest when females have high fecundity or low fertility. Fertility gains also vary spatially, as we find an additional strong effect of the stream from which females were collected. Responses were unaffected by male mating history (males kept with females or in male‐only groups). Recent male mating may be of lesser importance because males in many species, including T. dalmanni, partition their ejaculate to maintain their fertility over many matings. This study highlights the importance of complementing laboratory studies with data on wild‐caught populations, where there is considerable heterogeneity between individuals. Future research should focus on environmental, demographic and genetic factors that are likely to significantly influence variation in individual female fecundity and fertility.

Europe-wide consistency in density-dependence of red deer (Cervus elaphus) fertility

Population dynamics of large herbivores are affected by density dependent and density independent processes. Changing population size causes variation in age- and sex-specific demographic parameters such as reproduction, survival and dispersal. With our study, based on meta-analyses of literature data, we aimed at (1) describing age-specific fertility rates of red deer (Cervus elaphus) throughout Europe, and (2) tracking negative density feedback in reproduction of female red deer. Across the species range, in most European populations (84%) females began breeding as yearlings. We observed age-specific variation in female fertility, which was the lowest and most diverse in yearling females. Increasing population density had a negative effect on female fertility in all age groups. There was no difference in the strength of the relationship between different age classes of females. In 1.5-year old females, at low and moderate densities, fertility exhibited a high variation, which could indicate strong susceptibility of youngest females to detrimental external factors. Our study showed that meta-analysis of Europe-wide data was able to detect biologically relevant relationships which may be difficult to observe when applying locally-based and time-scale approach.

Residential segregation and the fertility of immigrants and their descendants

AbstractMeasures of community population composition, such as residential segregation, are important theoretical mechanisms that have the potential to explain differences in fertility between immigrants, their descendants, and destination natives. However, only a handful of studies explore these mechanisms, and most are limited by the fact that they carry out cross‐sectional analysis. This study proposes a new approach, which focuses on community composition in childhood. It uses longitudinal census data and registered births in England and Wales to investigate the relationship between completed fertility and multiple measures of community composition, including residential segregation. The results show that the fertility of immigrants is closer to native fertility if they grow up in less segregated areas. This provides evidence in support of the childhood socialisation hypothesis. Furthermore, residential segregation explains some of the variation in completed fertility for second‐generation women from Pakistan and Bangladesh, the only second‐generation group to have significantly higher completed fertility than natives. This suggests one reason why the fertility of some South Asians in England and Wales may remain “culturally entrenched.” All of these findings are consistent for different measures of community composition. They are also easier to interpret than the results of previous research because exposure is measured before childbearing has commenced, therefore avoiding many issues relating to selection, simultaneity, and conditioning on the future.

Three representative inter and intra-subspecific crosses reveal the genetic architecture of reproductive isolation in rice.

Systematic characterization of genetic and molecular mechanisms in the formation of hybrid sterility is of fundamental importance in understanding reproductive isolation and speciation. Using ultra-high-density genetic maps, 43 single-locus quantitative trait loci (QTLs) and 223 digenic interactions for embryo-sac, pollen, and spikelet fertility are depicted from three crosses between representative varieties of japonica and two varietal groups of indica, which provide an extensive archive for investigating the genetic basis of reproductive isolation in rice. Ten newly detected single-locus QTLs for inter- and intra-subspecific fertility are identified. Three loci for embryo-sac fertility are detected in both Nip×ZS97 and Nip×MH63 crosses, whereas QTLs for pollen fertility are not in common between the two crosses thus leading to fertility variation. Five loci responsible for fertility and segregation distortion are observed in the ZS97×MH63 cross. The importance of two-locus interactions on fertility are quantified in the whole genome, which identify that three types of interaction contribute to fertility reduction in the hybrid. These results construct the genetic architecture with respect to various forms of reproductive barriers in rice, which have significant implications in utilization of inter-subspecific heterosis along with improvement in the fertility of indica-indica hybrids at single- and multi-locus level.

Gender equality and family changes in the work–family culture in Southern Europe

ABSTRACTThe wider context of the trade-off between work and family is not just a matter of changing preferences. The focus of the literature in this area has been strongly concerned with the identification of factors promoting high levels of female employment than with the location of policy determinants of cross-national fertility variation. Work–family reconciliation is considered as a political action that gives quite limited and unstable support to encourage women’s labour market participation, this results in the poor development of external services and in fewer benefits for women, who have to undertake multiple roles inside and outside the family. The Southern European countries (SEC) model take a specific family-oriented approach to work–family reconciliation. They are family-oriented in that they entrust the family with more responsibilities that in other countries and take a conservative/corporatist-family-oriented approach to work–family reconciliation. The key role and the interconnection between fertility and employment among women, as well as the influence of the gender system and, on the whole, of the welfare system depend on the specific culture of different countries. Based on these theoretical premises, this paper reviews the academic discussion of the meaning of work–family balance concept in the cultural context of SEC from a comparative perspective, taking in account the gender equality debate.

Childlessness and fertility by couples' educational gender (in)equality in Austria, Bulgaria, and France

Background: In modern, highly developed countries the association between education and fertility seems to be equivocal: A negative influence of education mainly applies to women, while among men the correlation is often positive or negligible. Although the gender differences have been examined in depth, couples’ procreative behaviour treated as the result of a conflict between male and female characteristics is still understudied. Objective: This study aims to investigate couples’ reproductive behaviour among contemporary European populations with regard to (in)equality between partners’ educational levels and the joint educational resources of a couple. Various measures of educational endogamy are considered. Methods: The hurdle zero-truncated Poisson model within the Bayesian framework is applied. The data comes from the first wave of the Generations and Gender Survey for Austria, Bulgaria, and France. Results: Homogamous low-educated partners have, on average, the highest fertility. The highly educated postpone childbearing and have a smaller number of children in all countries except France, where their completed fertility does not differ from that of other unions. The effect of hypergamy is insignificant and is thus similar to homogamy in medium education. Hypogamy negatively influences fertility in Bulgaria and Austria, while in France the effect is insignificant. Conclusions: The small variation in fertility due to couple-level education observed in France indicates that proper institutional support for families might help couples overcome possible obstacles and enhance fertility for all educational profiles. Contribution: This study provides a perspective on the relationship between reproductive behaviour and educational pairing in varying country-specific contexts. It reaches key conclusions on contemporary fertility regarding both childlessness and parenthood and their association with couples’ different educational profiles.

Soybean response to NPK fertilization of sowing and potassium at topdressing in soil of improved fertility

The introduction of indeterminate habit soybean cultivars expanded the possibilities of rotation or succession crops in producing areas of the Cerrado region, but it represents a less well-known component in the management of soil fertility. The objective of this work was to verify the agronomic and economic response of indeterminate habit soybean to the variations in NPK fertilization of sowing and potassium at topdressing in an improved fertility Latosol in Campos das Vertentes (MG). The experimental design was in randomized blocks, with subdivided plots in three replications. In plots, the treatments consisted of doses of 315 and 485 kg ha-1 of NPK 02-30-10 formulation in the sowing furrow and, in the subplots, the application of 0, 15, 30 and 45 kg ha-1 of K2O in topdressing at 21 days after sowing was tested. There is no significant difference in the variation of sowing fertilization, but productivity increases linearly by the additional input of potassium at topdressing. Soybean cultivar requires more K2O in maintenance fertilization in soil of improved fertility to express productive potential near 4 t ha-1, which is economically rewarding.

DISTRIBUTION AND POPULATION STRUCTURE OF THE INVASIVE AMPHIPOD GMELINOIDES FASCIATUS (STEBBING) IN LAKE ONEGO

Since the middle of the ХХ century, the rapid spread of exotic species and their successful penetration in natural and artificial ecosystems has led to significant environmental changes all over the world [1, 2]. As it was pointed out by many researchers, biological invasion by alien species is one of the main threats to biodiversity [3, 4, 5, 6, 7]. Gmelinoides fasciatus (Stebbing 1899) attracts special attention due to the fact that it is the most successful alien species among other invaders in aquatic ecosystems in Eurasia. This invasive amphipod of Baikalian origin was first recorded in Lake Onego in 2001 by Berezina and Panov [8]. The results of the present study indicate that the invader significantly expanded its areal in Lake Onego during the last 15 years. At present amphipod G. fasciatus is dominant on the biomass among macrozoobenthos community in littoral biotopes of some islands and east part of the Lake. In Lake Onego the invader has a one-year life cycle with the generations of the previous and current year. Seasonal dynamics of the amphipod abundance in Lake Onego has two peaks during the vegetation period. According to our data G. fasciatus successfully reproduces in the new environment and shows stable sexual structure with sex ratio of approximately 1:1. Female fecundity of the amphipod in the Lake varied from 3 to 22 eggs per female, the average variation of fertility is 9 eggs per female. Revealed data of G. fasciatus abundance and biomass in Lake Onego are comparable with those for other water bodies where this amphipod species was successfully established earlier.

Can Women Have Children and a Career? IV Evidence from IVF Treatments.

This paper introduces a new IV strategy based on IVF (in vitro fertilization) induced fertility variation among childless women to estimate the causal effect of having children on their career. For this purpose, we use administrative data on IVF treated women in Denmark. Because observed chances of IVF success do not depend on labor market histories, IVF treatment success provides a plausible instrument for childbearing. Our IV estimates indicate that fertility effects on earnings are: (i) negative, large, and long-lasting; (ii) driven by fertility effects on hourly earnings and not so much on labor supply; and (iii) much stronger at the extensive margin than at the intensive margin.

Fertility and Its Meaning: Evidence from Search Behavior

Fertility choices are linked to the different preferences and constraints of individuals and couples, and vary importantly by socio-economic status, as well by cultural and institutional context. The meaning of childbearing and childrearing, therefore, differs between individuals and across groups. In this paper, we combine data from Google Correlate and Google Trends for the U.S. with ground truth data from the American Community Survey to derive new insights into fertility and its meaning. First, we show that Google Correlate can be used to illustrate socio-economic differences on the circumstances around pregnancy and birth: for example, searches for “flying while pregnant” are linked to high income fertility, and “paternity test” are linked to non-marital fertility. Second, we combine several search queries to build predictive models of regional variation in fertility, explaining about 75% of the variance. Third, we explore if aggregated web search data can also be used to model fertility trends.

Prospects for Fertility Decline in Africa

Prospects for Fertility Decline in Africa

Religiosity and Fertility: Jews in Israel.

We analyze the relationship between religiosity and fertility among Jews in Israel-a modern democracy in which there is no separation of religion and state. Micro-level data from the 2009 Israel Social Survey are used to perform multivariate analyses of the odds of having at least three children. The findings from separate analyses of women and men are consistent with a theoretical framework, outlined by McQuillan and C. Goldscheider, which suggests how religiosity affects fertility. In particular, measures of the importance of religious community explain in part the higher levels of fertility among some religiosity groups; attitudes toward religion as a social and political institution as well as norms regarding family building over the life course also partly account for the influence of religiosity on fertility. While women's employment activity is significantly related to their fertility, as many economic theories predict, controlling for paid work in regression models does not affect the estimated relationship between religiosity and women's fertility. We conclude that, in the current context, fertility variation across religiosity groups can be understood largely in terms of the cultural, political, and institutional power of religion, and the impact of religion through community, and via norms and ideals.

Association of single nucleotide polymorphisms in candidate genes previously related to genetic variation in fertility with phenotypic measurements of reproductive function in Holstein cows

Many genetic markers related to health or production traits are not evaluated in populations independent of the discovery population or related to phenotype. Here we evaluated 68 single nucleotide polymorphisms (SNP) in candidate genes previously associated with genetic merit for fertility and production traits for association with phenotypic measurements of fertility in a population of Holstein cows that was selected based on predicted transmitting ability (PTA) for daughter pregnancy rate (DPR; high, ≥1, n = 989; low, ≤ -1.0, n = 1,285). Cows with a high PTA for DPR had higher pregnancy rate at first service, fewer services per conception, and fewer days open than cows with a low PTA for DPR. Of the 68 SNP, 11 were associated with pregnancy rate at first service, 16 with services per conception, and 19 with days open. Single nucleotide polymorphisms in 12 genes (BDH2, BSP3, CAST, CD2, CD14, FUT1, FYB, GCNT3, HSD17B7, IBSP, OCLN, and PCCB) had significant associations with 2 fertility traits, and SNP in 4 genes (CSPP1, FCER1G, PMM2, and TBC1D24) had significant associations with each of the 3 traits. Results from this experiment were compared with results from 2 earlier studies in which the SNP were associated with genetic estimates of fertility. One study involved the same animals as used here, and the other study was of an independent population of bulls. A total of 13 SNP associated with 1 or more phenotypic estimates of fertility were directionally associated with genetic estimates of fertility in the same cow population. Moreover, 14 SNP associated with reproductive phenotype were directionally associated with genetic estimates of fertility in the bull population. Nine SNP (located in BCAS, BSP3, CAST, FUT1, HSD17B7, OCLN, PCCB, PMM2, and TBC1D24) had a directional association with fertility in all 3 studies. Examination of the function of the genes with SNP associated with reproduction in more than one study indicates the importance of steroid hormones and immune function as determinants of reproductive function. All but 1 of the 68 evaluated SNP were variable in 11 breeds besides Holstein, indicating the potential effects of these SNP on reproductive function across breeds of cattle.

The annual carnival in Guadeloupe (French West Indies) is associated with an increase in the number of conceptions and subsequent births nine months later: 2000 - 2011.

The seasonal patterns of conceptions and births differ between geographic areas. Several potential determinants of this variation have been identified, including biological, environmental and behavioral elements, but festive events are rarely mentioned. We investigated the possible association between the carnival and seasonal fertility variations in the French West Indies. We ran a retrospective registry-based study. The data were extracted from the registry of all births on Guadeloupe between 2000 and 2011 (n = 74,412), and from the Maternity Birth Register of the University Hospital, for all pregnancies of at least 14 completed weeks of gestation (observable conceptions) with an outcome recorded between 2007 and 2010 (n = 8,425). We compared data during and outside the carnival period for each year, including 2009, when there was no carnival due to a 44-day general strike. In all years other than 2009, the weekly number of births was higher for pregnancies initiated during the carnival period than for pregnancies initiated at other times, and the weekly number of observable conceptions was higher during the carnival period than at other times. Our findings support the hypothesis that carnivals in the French West Indies are associated with an increase in the number of conceptions and subsequent births.

Women's Agency and Fertility: Recent Evidence from Egypt.

Fertility reached a two decade high of 3.5 births per woman in Egypt in 2014. Lower status of women is associated with higher fertility. Majority of the studies on women's agency and fertility rely on individual level cross-sectional data from South Asia, which limits the understanding of variation among communities and the direction of the relationship between women's agency and fertility in other global contexts. This study examines the relationship between women's agency and fertility longitudinally and among communities in the most populous country in the Middle East - Egypt. For 3,795 ever married women 15 to 49 years old in the 2006 and 2012 Egyptian Labor Market Panel Survey, multilevel models are estimated for having given birth and number of births between 2006 and 2012. Contrary to expectation, women with more agency with greater participation in household decision-making and mobility are, in fact, more likely to have had a birth and have a greater total number of births. Only women with more egalitarian attitudes are associated with fewer births. Community membership explains 5% of the variation in fertility. Since social norms in Egypt favor a higher number of births and labor market participation among women is low, women with agency could be fulfilling social expectations of having children and choosing to have more children.