Differences In Fertility Research Articles

Assessing the potential for post-ejaculatory female choice in a polyandrous beach-spawning fish.

In species with limited opportunities for pre-ejaculatory sexual selection (behavioural components), post-ejaculatory mechanisms may provide opportunities for mate choice after gametes have been released. Recent evidence from a range of taxa has revealed that cryptic female choice (i.e., female-mediated differential fertilization bias), through chemical cues released with or from eggs, can differentially regulate the swimming characteristics of sperm from various males and ultimately determine male fertilization success under sperm competition. We assessed the potential role that such female-modulated chemical cues play in influencing sperm swimming characteristics in beach-spawning capelin (Mallotus villosus), an externally fertilizing fish that mates as couples (one male and one female) or threesomes (two males and one female) with presumably limited opportunities for pre-ejaculatory sexual selection. We assayed sperm swimming characteristics under varying doses and donor origins of egg cues and also examined the possibility of assortative mating based on body size. We found mating groups were not associated by size, larger males did not produce better quality ejaculates, and egg cues (regardless of dosage or donor identity) did not influence sperm swimming characteristics. Our findings suggest that intersexual pre-ejaculatory sexual selection and cryptic female choice mediated by female chemical cues are poorly developed in capelin, possibly due to unique natural selection constraints on reproduction.

Technical devices used for differential fertilizer application

The purpose of this article is to describe new technical devices for differential application of fertilizers taking into account heterogeneity of the thickness of the humus horizon. Modern fertilizer application technologies are based on information obtained from agrochemical soil surveys, space monitoring data and the NDVI index. At the same time, all these technologies do not take into account physical and mechanical properties of the soil which influence soil fertility and productivity. The article presents data on the relationship between soil hardness and thickness of the humus horizon which have a strong inverse correlation of the -0.7-0.85 order. Based on these data, technical devices used for differential fertilizer application were designed taking into account power of the humus horizon.

A geographically weighted regression approach to examine the dynamics of fertility differentials across Africa

Studies have shown that fertility rate in Africa is still among the highest in the world. However, there are few spatial investigations into the variation of fertility rate and its determinant in Africa. This study aimed to examine the spatial distribution of fertility rate as well as highlight its significant determinants. Ordinary Least Squares (OLS) regression was carried out on dataset for 53 African countries on Total Fertility Rate (TFR) and eleven determinant factors to obtain a best model, which was then used for Geographically Weighted Regression (GWR). The study showed that TFR was significantly influenced by adolescent fertility rates, contraceptive prevalence rates and gross domestic product per capita. GWR model diagnostics of Akaike Information Criterion and adjusted R-squared showed that GWR fitted TFR in Africa better than OLS model. Also, countries around Middle to Western Africa comprising Burundi, Democratic Republic of the Congo, Central African Republic, Chad, Nigeria, Niger, Benin, Burkina Faso and Mali, were regions with high TFRs that impacted Africa’s positive TFR spatial autocorrelation. More intense works could therefore be carried out in these countries to manage the identified significant factors affecting TFR to address the negative consequences of high TFR in Africa.

Rainfall risk, fertility and development: evidence from farm settlements during the American demographic transition

Abstract I analyze whether variation in rainfall risk played a role in the demographic transition. The hypothesis is that children constituted a buffer stock of labor that could be mobilized in response to income shocks. Identification relies on fertility differences between farm and non-farm households within counties and over time. The results suggest that in areas with a high variance in rainfall the fertility differential was significantly higher than in areas with a low variance in rainfall. This channel is robust to other relevant forces and the spatial correlation in fertility. The effect disappeared as irrigation systems and agricultural machinery emerged.

Measuring Selection Intensities Among Kolam Population: Manifested through Differential Fertility and Differential Mortality

The objective of the study is to understand the selection intensities among Kolam, a particularly vulnerable tribal group (PVTG) of Adilabad district of Telangana State, India. Two prominent methods were employed to understand the intensities by using Crow’s index and modified formula as given by Johnston and Kensinger’s method. The intensities are computed on the basis of the reproductive history of mother with completed fertility and the results were compared with the available works on populations belonging to Andhra Pradesh, Telangana and India. The Crow’s total index (II) value was found to be 0.3863. The mortality (Im) component was found to be 0.2151 while fertility (If) component was found to be 0.1712. The contribution of mortality component is greater than that of fertility component among the present studied population using Crow’s index. According to Johnston and Kensinger, the total index (II) was found to be 0.6017. Fertility component was found to be 0.2368, prenatal mortality component (Ime) and postnatal mortality component (Ime/Pb) where observed to be 0.0675 and 0.0933 respectively. Therefore, it is clear from the results that postnatal mortality contributes more than prenatal mortality for selection, i.e., Johnston and Kensinger’s Index (0.6017) contributes more towards selection intensity than Crow’s index (0.3863). Natural selection takes place when there is variability of fitness observed through the differences in fertility and mortality in any population.

Sex Preference, Religion and Ethnicity Roles in Fertility Among Women of Childbearing Age in Nigeria: Examining the Links Using Zero-Inflated Poisson Regression Model

The study aimed at examining the independent and joint influence of three cultural factors; religion, sex preference (SP) and ethnicity on fertility in Nigeria. Cross-sectional population-based cluster design approach was used for the study. The investigated population group was women of reproductive age (n=19,348). Probability of bearing ≥5 children, refined Total Fertility Rate and mean fertility were used to assess fertility. Data were analyzed using demographic and Zero-Inflated Poisson models. Fertility indices were higher among the Hausa/Fulani ethnic group than Igbo and Yoruba and also among Muslim women than Christians. Interaction shows that the probability of bearing at least five children was highest among women who; have no SP, belong to Islamic religious denomination, and of Hausa/Fulani ethnic group. The fertility incident rate ratio (IRR) was higher among women with no SP than women who have SP and also higher among Hausa/Fulani than Yoruba but lower among Christians than Muslims. Fertility differentials persists by ethnicity, religion and SP after controlling for other important variables. Difference exists in fertility among religious, ethnic groups and by SP in Nigeria. Fertility reduction strategies should be intensified in Nigeria, but more attention should be given to Muslims and Hausa/Fulani women.

Sex Preference, Religion and Ethnicity Roles in Fertility Among Women of Childbearing Age in Nigeria: Examining the Links Using Zero-Inflated Poisson Regression Model

The study aimed at examining the independent and joint influence of three cultural factors; religion, sex preference (SP) and ethnicity on fertility in Nigeria. Cross-sectional population-based cluster design approach was used for the study. The investigated population group was women of reproductive age (n=19,348). Probability of bearing ≥5 children, refined Total Fertility Rate and mean fertility were used to assess fertility. Data were analyzed using demographic and Zero-Inflated Poisson models. Fertility indices were higher among the Hausa/Fulani ethnic group than Igbo and Yoruba and also among Muslim women than Christians. Interaction shows that the probability of bearing at least five children was highest among women who; have no SP, belong to Islamic religious denomination, and of Hausa/Fulani ethnic group. The fertility incident rate ratio (IRR) was higher among women with no SP than women who have SP and also higher among Hausa/Fulani than Yoruba but lower among Christians than Muslims. Fertility differentials persists by ethnicity, religion and SP after controlling for other important variables. Difference exists in fertility among religious, ethnic groups and by SP in Nigeria. Fertility reduction strategies should be intensified in Nigeria, but more attention should be given to Muslims and Hausa/Fulani women.

The "maternal effect" on epilepsy risk: Analysis of familial epilepsies and reassessment of prior evidence.

Previous studies have observed that epilepsy risk is higher among offspring of affected women than offspring of affected men. We tested whether this "maternal effect" was present in familial epilepsies, which are enriched for genetic factors that contribute to epilepsy risk. We assessed evidence of a maternal effect in a cohort of families containing ≥3 persons with epilepsy using 3 methods: (1) "downward-looking" analysis, comparing the rate of epilepsy in offspring of affected women versus men; (2) "upward-looking" analysis, comparing the rate of epilepsy among mothers versus fathers of affected individuals; and (3) lineage analysis, comparing the proportion of affected individuals with family history of epilepsy on the maternal versus paternal side. Downward-looking analysis revealed no difference in epilepsy rates among offspring of affected mothers versus fathers (prevalence ratio = 1.0, 95% confidence interval [CI] = 0.8-1.2). Upward-looking analysis revealed more affected mothers than affected fathers; this effect was similar for affected and unaffected sibships (odds ratio = 0.8, 95% CI = 0.5-1.2) and was explained by a combination of differential fertility and participation rates. Lineage analysis revealed no significant difference in the likelihood of maternal versus paternal family history of epilepsy. We found no evidence of a maternal effect on epilepsy risk in this familial epilepsy cohort. Confounding sex imbalances can create the appearance of a maternal effect in upward-looking analyses and may have impacted prior studies. We discuss possible explanations for the lack of evidence, in familial epilepsies, of the maternal effect observed in population-based studies. ANN NEUROL 2020;87:132-138.

Mudanças na fecundidade adolescente segundo escolaridade entre 1991 e 2010 no Brasil

O Brasil experimentou recentemente declínio da fecundidade adolescente e aumento da cobertura escolar. Neste contexto, os diferenciais da fecundidade na adolescência segundo grupos educacionais podem diminuir ou mesmo aumentar. Diantedas possibilidades em se observar diferentes tendências dos diferenciais de fecundidade das adolescentes segundo níveis de escolaridade, o objetivo deste trabalho é comparar tais diferenciais, controlados por variáveis demográficas e socioeconômicas, em 1991, 2000 e 2010 no Brasil. Usando dados do Censo Demográfico Brasileiro e estimativas de regressão logística, os principais resultados mostram aumentos consecutivos entre os diferenciais da chance de ser mãe adolescente segundo escolaridade, indicando uma tendência de crescimentos dos diferenciais entre os censos. Desta forma, adolescentes com baixa escolaridade apresentaram uma piora crescente em suas chances de inibir a fecundidade se comparadas às adolescentes com nove anos ou mais de escolaridade.

Differential Sperm Motility Mediates the Sex Ratio Drive Shaping Mouse Sex Chromosome Evolution.

SummaryThe mouse sex chromosomes exhibit an extraordinary level of copy number amplification of postmeiotically expressed genes [1, 2], driven by an “arms race” (genomic conflict) between the X and Y chromosomes over the control of offspring sex ratio. The sex-linked ampliconic transcriptional regulators Slx and Sly [3, 4, 5, 6, 7] have opposing effects on global transcription levels of the sex chromosomes in haploid spermatids via regulation of postmeiotic sex chromatin (PMSC) [8, 9, 10, 11] and opposing effects on offspring sex ratio. Partial deletions of the Y chromosome (Yq) that reduce Sly copy number lead to global overexpression of sex-linked genes in spermatids and either a distorted sex ratio in favor of females (smaller deletions) or sterility (larger deletions) [12, 13, 14, 15, 16]. Despite a large body of work studying the role of the sex chromosomes in regulating spermatogenesis (recent reviews [17, 18, 19, 20]), most studies do not address differential fertility effects on X- and Y-bearing cells. Hence, in this study, we concentrate on identifying physiological differences between X- and Y-bearing sperm from Yq-deleted males that affect their relative fertilizing ability and consequently lead to sex ratio skewing. We show that X- and Y-bearing sperm in these males have differential motility and morphology but are equally able to penetrate the cumulus and fertilize the egg once at the site of fertilization. The altered motility is thus deduced to be the proximate cause of the skew. This represents the first demonstration of a specific difference in sperm function associated with sex ratio skewing.

"Cementing" marriages through childbearing in subsequent unions: Insights into fertility differentials among first-time married and remarried women in Ghana.

Fertility in Ghana has declined steadily since 1980, however, a slight increase was observed between 2008 and 2014. While several factors may account for this pattern, research on the contribution of type of union is limited. This study examined differentials in the fertility of women in different types of union. Secondary data from 6,285 (weighted) ever-married women aged 15–49 years were analysed using compare means, t-test, analysis of variance, Poisson and binary logistic regression analyses. The findings indicate that, independent of other factors, fertility among remarried women is higher compared to first-time married women but this does not hold true when other factors are controlled for. Additionally, there was no significant difference in the fertility of remarried women who were in union and women who were in union in a first-time marriage. However, compared to remarried women who were currently in a union, fertility was significantly lower among remarried women who were not currently in union (β = -0.121, p<0.01) and women who have been married only once but were not currently in union (β = -0.212, p<0.001). Further analysis revealed that remarried women were significantly more likely to desire more children and less likely to use any method of contraception compared to first-time married women. There is the need for further research to better understand the fertility needs of remarried women.

Fertility of Pedicellate Spikelets in Sorghum Is Controlled by a Jasmonic Acid Regulatory Module.

As in other cereal crops, the panicles of sorghum (Sorghum bicolor (L.) Moench) comprise two types of floral spikelets (grass flowers). Only sessile spikelets (SSs) are capable of producing viable grains, whereas pedicellate spikelets (PSs) cease development after initiation and eventually abort. Consequently, grain number per panicle (GNP) is lower than the total number of flowers produced per panicle. The mechanism underlying this differential fertility is not well understood. To investigate this issue, we isolated a series of ethyl methane sulfonate (EMS)-induced multiseeded (msd) mutants that result in full spikelet fertility, effectively doubling GNP. Previously, we showed that MSD1 is a TCP (Teosinte branched/Cycloidea/PCF) transcription factor that regulates jasmonic acid (JA) biosynthesis, and ultimately floral sex organ development. Here, we show that MSD2 encodes a lipoxygenase (LOX) that catalyzes the first committed step of JA biosynthesis. Further, we demonstrate that MSD1 binds to the promoters of MSD2 and other JA pathway genes. Together, these results show that a JA-induced module regulates sorghum panicle development and spikelet fertility. The findings advance our understanding of inflorescence development and could lead to new strategies for increasing GNP and grain yield in sorghum and other cereal crops.

Understanding How Immigrant Fertility Differentials Vary over the Reproductive Life Course

Studies of immigrant fertility differentials indicate that foreign-born women have more children than native-born women, at least for some origin groups. Yet little is known about variation in cumulative fertility differentials over the life course, including the extent to which this variation develops into completed fertility differentials. This research responds with an analysis of cumulative fertility differentials in the UK for a cohort of women born between 1942 and 1971. Findings are consistent with age-specific patterns that have been documented for immigrant groups in the UK, but underline the importance of taking a cohort perspective, which helps to distinguish between the tempo and quantum of fertility. Immigrants have significantly higher completed fertility than UK-born natives if they were born in India, Pakistan, Bangladesh, Jamaica, or Western and Central Africa, but the profile of their cumulative fertility differentials—versus the UK-born—varies considerably over the life course, especially by age at migration. For example, women from Bangladesh and Pakistan have similar levels of cumulative fertility at age 40, but very different age patterns of cumulative fertility from ages 20–40. There is a consistent pattern of relatively delayed Pakistani fertility at early ages, especially for those arriving at later ages, but the same is not true for women from Bangladesh. Overall, these results imply that researchers should beware of variation in cohort fertility over the life course—with respect to both the quantum and tempo of fertility—when analysing immigrant childbearing, in addition to variation by origin and age at arrival.

High potential of variable rate fertilization combined with a controlled released nitrogen form at affecting cv. Barbera vines behavior

Abstract Variable rate technologies allow site-specific management of parcels characterized by different levels of vigor and/or yield. Fertilization based on actual plant needs is one of the most promising applications of precision farming aiming at improving efficiency, optimizing vine balance, as well as limiting environmental impact. Although this strategy appears suitable for developing new vineyard management models, few experiences validating this hypothesis are available in the literature. Based on a pre-trial remotely sensed vigor map (NDVI-derived, 5 m resolution), a three-year study was performed in a Vitis vinifera L. cv. Barbera vineyard situated in the Colli Piacentini area. Vigor level (L = low, M = medium and H = high) and fertilization technique (Standard, Variable Rate Application, and unfertilized Control) were the main factors in a randomized block design. The controlled release fertilizer Multicote™ Agri ([NPK fertilizer 13-5-21 + 7MgO+14SO3 (Controlled Release Nitrogen >46% on the total nitrogen, with longevity 2÷4 months), low in chloride] was used and the input rate calculated according to the N-supply. For each vigor level the study compared no fertilization (0 kg/ha), standard supply (40 kg of N /ha) and Variable Rate Application (VRA) supply delivering 0, 40 and 80 kg of N/ha to H, M and L, respectively. Vine growth, yield, leaf nutritional status and fruit composition were assessed. Results show that the classified L vigor plots had significantly less growth (i.e leaf area or pruning weight per vine) than M and H vigor plots, whereas yield components and grape composition followed a linear variation with vigor. There was a large prevalence of vigor x technique interactions suggesting that VRA had a differential impact on vine behavior depending upon the initial level of vigor. For vegetative and yield parameters, in the L vigor vines, increased Multicote™ Agri dosage delivered as control (0 kg of N/ha), standard (40 kg of N/ha) and VRA (80 kg of N/ha) caused a very close and linear increase in total leaf and yield per vine, whereas, within the M and H vigor plots, the effect due to fertilization technique was very mild. Such a behavior was nicely mirrored by grape composition at harvest as, in L vines, applying 40 or 80 kg of N in the form of Multicote™ Agri induced a progressive and significant reduction in both must soluble solids and total anthocyanins concentration, although the oenological quality of the resulting must was still satisfactory and in compliance with the oenological target. The novelty of the present work is that, unlike previous variable rate fertilization attempts where a rapid nitrogen release fertilizer such as urea was used, L vigor vines showed a very prompt response to the amount of Multicote™ Agri application, confirming higher effectiveness of this chemical form and higher flexibility in adjusting the level of vigor and yield according to specific needs. Conversely, when the initial level of vigor was medium or high, differential fertilization resulted in overall minor modifications of the vine behavior.

Is Selection Necessary for Evolution? A Dynamics of Coastal Population of India

Nature provides a good opportunity to understand the dynamics of evolution. The country has a huge coastline, which experiences socio-cultural and natural vulnerability. The aim of the paper has been to describe the pattern of selection intensity among the east and west coastal populations of India. Differential fertility and mortality were collected from 2,099 females (mothers) of the western coasts of India, and secondary data were collected from the eastern coast of India for comparison purposes. Selection potential was computed using Crow’s index and Johnston &amp; Kensinger’s index. The data involved a total of 7,512 pregnancies during their reproductive lifespan and the successful outcomes (live births) were 7,073. The total index (It) for eastern coast varied from 0.221 to 1.078. For the west coast, it varied from 0.262 to 0.617. Among the eastern coastal population groups, the mortality component of selection is comparatively higher than its fertility component, while it is just the reverse among the western coastal population groups.

Reading the geography of India's district-level fertility differentials: a spatial econometric approach.

India has gradually progressed into fertility transition over the last few decades. However, the timing and pace of this transition has varied notably in terms of both its geography and the demographic groups most affected by it. While much literature exists on the relationships between fertility level and its influence on demographic, economic, socio-cultural and policy-related factors, the potential spatial variations in the effects of these factors on the fertility level remain unaddressed. Using the most recent district-level census data (of 2011) for India, this nationwide study has identified plausible spatial dependencies and heterogeneities in the relationships between the district-wise Total Fertility Rates (TFRs) and their respective demographic, socioeconomic and cultural factors. After developing a geocoded database for 621 districts of India, spatial regression and Geographically Weighted Regression (GWR) models were used to decipher location-based relationships between the district-level TFR and its driving forces. The results revealed that the relationships between the district-level TFR and the considered selected predictors (percentage of Muslims, urbanization, caste group, female mean age at marriage, female education, females in the labour force, net migration, sex ratio at birth and exposure to mass media) were not spatially invariant in terms of their respective strength, magnitude and direction, and furthermore, these relationships were conspicuously place- and context-specific. This study suggests that such locality-based variations and their complexities cannot be explained simply by a single narrative of either socioeconomic advancement or government policy interventions. It therefore contributes to the ongoing debate on fertility research in India by highlighting the spatial dependence and heterogeneity of the impacts made by demographic, socioeconomic and cultural factors on local fertility levels. From a methodological perspective, the study also discerns that the GWR local model performs better, in terms of both model performance and prediction accuracy, compared with the conventional global model estimates.

Positive Consequences of Declining Fertility: Socioeconomic Analysis of Punjab, Pakistan

Objectives: The present paper attempted to discover the behaviour of fertility differentials across the districts of Punjab, Pakistan. More precisely, it aimed to investigate some salient determinants of fertility differential through fitted regression line and scatter plot including the confidence interval. Materials and Methods: Data in this study were gathered from Multiple Indicator Cluster Survey 2013-2014. The regression analysis was employed to evaluate the relationship of fertility determinants, followed by plotting two-way scatter plots and confidence intervals. For the empirical analysis, the total fertility rate (TFR) was taken as an outcome variable while the employment rate, underfive mortality, and contraceptive use were considered as determinants. Results: The results indicated that child mortality is a very significant variable in determining the level of fertility and it had the coefficient value of 0.0096. It was further found that child mortality has a positive relationship with fertility rates. Thus, child mortality must be reduced to overcome the issue of high fertility rates at the district level of Punjab. Contraceptive use was also a very effective variable regarding determining the level of fertility and had a negative coefficient value of -0.033. Finally, the employment rate was a very useful variable for the determination of fertility level. Conclusions: The empirical results revealed that child mortality should be reduced in order to decrease the level of fertility in Punjab, Pakistan, and contraceptive use should develop through family planning programs.

Toward a Theory of Fertility and Ethnic Social Capital

The purpose of this paper is to develop a conceptual model of ethnic fertility differentials that incorporates the intersection of both the macro societal influences as well as the micro actor level influences. It first contextualizes ethnic fertility differentials within the global fertility decline literature. Then it reviews the extant theories of fertility decline. It then turns to an examination of fertility choices in the developed world. A summary of three major approaches to ethnic fertility differentials is examined and then incorporated into a more eclectic perspective provided by Goldscheider. Finally, this paper merges the Goldscheider perspective with the social capital perspective, as applied to fertility decisions, into a conceptual model of ethnic fertility differentials. Lastly, the new conceptual model is used to reflect upon the current state of global fertility decline.

Effects of son preference on fertility: A parity progression analysis

This article assesses the strength of son preference in Bangladesh, as reflected in fertility behavior. Although the fertility rate for Bangladesh declined from 6.3 children per woman of reproductive age in the year 1975 to 2.3 children in 2014, empirical results show that son preference has still a strong influence on fertility behavior. Keeping cognizant of this fact, this study examines levels and differentials in fertility and also investigates the effects of son preference on fertility in Bangladesh. In addition, the study inspects the underlying factors responsible for son preference. Levels of fertility indicate that the proportion of higher education of a couple is inversely related to fertility, whereas rural and Muslim couples in Bangladesh have more children. The bivariate analysis shows that almost all the independent variables selected for this study have a significant association with parity progression. Findings from multivariate analyses suggest that women with at least one son are less likely to continue childbearing than women without sons at parities 2-3. At most or all parities, continued childbearing is negatively associated with education, access to mass media, and family wealth. A significant source of motivation for parity progression in couples is the desire to have a son.

Study on factors affecting fertility of Bangladeshi women

This is a cross sectional study conducted among Currently Married Women of Reproductive Age (CMWRA) with a sample size of 476 selected purposively using a semi-structured questionnaire in 2018 at Moulvibazar Sadar to explore the factors affecting fertility. The result shows that 55.26% respondents were within 35 years age whereas only 4.28% from age group 46-49 years age group, 33% of the respondents got married at &lt;16 years of age and 18.70% were illiterate, 47.90% had primary education. It is evident that 76% of the respondents were from rural area; 88% were Muslims, 29.41% from lower middle class followed by upper middle class (25.42%) and poorest comprised only 7.56%. The result explored that 73.91% of the respondents were from age group 41-45 got married before 16 years of age followed by 36-40 years (68.24%), 46-49 years (66%), 20-25 and 26-30 years age groups 52.38% and 52.75% respectively; 73.33% of respondents from rural area got married at &lt;16 years of age, 68.42% of the Muslim at &lt;16 years. The study explored that 96.39% from poorer section and 83.33% from poorest section got married at &lt;16 years of age. Current study revealed that 82.91% of the respondents having secondary education got married before 16 years of age followed by illiterate (82.02%). It is explored that the age at marriage is statistically associated with residence, education, wealth index and religion (p= 0.001, 0.03, 0.001, 0.001 respectively). We conclude that the sociodemographic condition contributes mostly to fertility differentials in Bangladesh.