Number of Children, Age At First Birth, Hormones

1996 ◽  
pp. 191-204
Author(s):  
Gabriel A. Kune
Keyword(s):  
Age At First Birth ◽  
First Birth ◽  
Number Of Children

Examining the link between religiousness and fitness in a behavioural ecological framework

2019 ◽  
Vol 52 (5) ◽  
pp. 756-767 ◽  
Author(s):  
Janko Međedović
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Parental Investment ◽  
Life History Theory ◽  
Community Sample ◽  
Future Research ◽  
Harsh Environment ◽  
Age At First Birth ◽  
First Birth ◽  
Number Of Children

AbstractIn recent years there have been attempts to explain religiousness from an evolutionary viewpoint. However, empirical data on this topic are still lacking. In the present study, the behavioural ecological theoretical framework was used to explore the relations between religiousness, harsh environment, fitness (reproductive success and parental investment) and fitness-related outcomes (age at first birth, desired number of children and the romantic relationship duration). The data were collected from 461 individuals from a community sample who were near the end of their reproductive phase (54% females, Mage = 51.75; SD = 6.56). Positive links between religiousness, harsh environment, fitness and fitness-related outcomes were expected, with the exception of age at first birth, for which a negative association was hypothesized. Hence, the main assumption of the study was that religiousness has some attributes of fast life-history phenotypes – that it emerges from a harsh environment and enables earlier reproduction. The study findings partially confirmed these hypotheses. Religiousness was positively related to environmental harshness but only on a zero-order level. Religious individuals had higher reproductive success (this association was especially pronounced in males) but religiousness did not show associations with parental investment. Religiousness was positively associated with desired number of children and negatively associated with age at first birth, although the latter association was only marginally significant in the multivariate analyses. Finally, path analysis showed that desired number of children and age at first birth completely mediated the relation between religiousness and reproductive success. The data confirmed the biologically adaptive function of religiousness in contemporary populations and found the mediating processes that facilitate fitness in religious individuals. Furthermore, the findings initiate a more complex view of religiousness in a life-history context which could be fruitful for future research: a proposal labelled as ‘ontogeny-dependent life-history theory of religiousness’.

scholarly journals Intelligence and Fitness: The Mediating Role of Educational Level

2017 ◽  
Vol 15 (2) ◽  
pp. 147470491770693 ◽  
Author(s):  
Janko Međedović
Keyword(s):  
Reproductive Success ◽  
Cognitive Abilities ◽  
Evolutionary Status ◽  
Age At First Birth ◽  
First Birth ◽  
Short Term ◽  
Number Of Children ◽  
Mediating Role ◽  
Fitness Indicators

The evolutionary status of intelligence is not clear: It is positively related to various indicators of fitness but negatively to reproductive success as the most important fitness marker. In the present research, we explored the links between intelligence and three fitness indicators: number of children (short-term reproductive success), number of grandchildren (long-term reproductive success), and age at first birth. Participants were individuals in a postreproductive stage ( N = 191; mean age = 66.5 years). Intelligence had a positive correlation with short-term reproductive success and age at first birth but a negative correlation with long-term reproductive success. Participants’ education turned out to be a significant mediator of the link between intelligence and criterion measures. The results showed that intelligence can elevate short-term reproductive success. Furthermore, individuals with higher intellectual abilities tended to delay reproduction, which negatively affected their long-term reproductive success. Education was revealed as a very important resource which affects the link between cognitive abilities and fitness, thus proving its evolutionary role in contemporary populations.

scholarly journals Schizophrenia risk and reproductive success: a Mendelian randomization study

2019 ◽  
Vol 6 (3) ◽  
pp. 181049 ◽  
Author(s):  
Rebecca B. Lawn ◽  
Hannah M. Sallis ◽  
Amy E. Taylor ◽  
Robyn E. Wootton ◽  
George Davey Smith ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Mendelian Randomization ◽  
Causal Effect ◽  
Sexual Partners ◽  
Age At First Birth ◽  
First Birth ◽  
Genetic Liability ◽  
Number Of Children ◽  
Fitness Advantage ◽  
Number Of Sexual Partners

Schizophrenia is a debilitating and heritable mental disorder associated with lower reproductive success. However, the prevalence of schizophrenia is stable over populations and time, resulting in an evolutionary puzzle: how is schizophrenia maintained in the population, given its apparent fitness costs? One possibility is that increased genetic liability for schizophrenia, in the absence of the disorder itself, may confer some reproductive advantage. We assessed the correlation and causal effect of genetic liability for schizophrenia with number of children, age at first birth and number of sexual partners using data from the Psychiatric Genomics Consortium and UK Biobank. Linkage disequilibrium score regression showed little evidence of genetic correlation between genetic liability for schizophrenia and number of children ( r g = 0.002, p = 0.84), age at first birth ( r g = −0.007, p = 0.45) or number of sexual partners ( r g = 0.007, p = 0.42). Mendelian randomization indicated no robust evidence of a causal effect of genetic liability for schizophrenia on number of children (mean difference: 0.003 increase in number of children per doubling in the natural log odds ratio of schizophrenia risk, 95% confidence interval (CI): −0.003 to 0.009, p = 0.39) or age at first birth (−0.004 years lower age at first birth, 95% CI: −0.043 to 0.034, p = 0.82). We find some evidence of a positive effect of genetic liability for schizophrenia on number of sexual partners (0.165 increase in the number of sexual partners, 95% CI: 0.117–0.212, p = 5.30×10 −10 ). These results suggest that increased genetic liability for schizophrenia does not confer a fitness advantage but does increase mating success.

scholarly journals European countries with delayed childbearing are not those with lower fertility

Genus ◽  
2021 ◽  
Vol 77 (1) ◽  
Author(s):  
Éva Beaujouan ◽  
Laurent Toulemon
Keyword(s):  
Context Effects ◽  
Negative Relationship ◽  
Age At First Birth ◽  
First Birth ◽  
Individual Level ◽  
Number Of Children ◽  
Country Level ◽  
Strong Negative Relationship ◽  
Lower Fertility ◽  
The Individual

AbstractAt the individual level, a very strong negative relationship is observed between age at first birth and total number of children. However, at the country level, it is possible that no relationship exists between factors that reduce fertility at younger ages and stimulate it at older ages. Hence, across countries, the size of the decline in youth fertility is potentially unrelated to the size of the increase in fertility at older ages or the decline in total fertility. We study the fertility of women and their age at childbirth, with particular attention to their evolution over the last 40 years in countries across Europe. Comparing these countries, the increase in births after age 30 has occurred relatively independently of the decline at younger ages according to both period and cohort, and we find no positive relationship between the delay of first birth and decline in total fertility. On the contrary, an inverse relationship evidently exists at the country level, as longer delays generally correspond to smaller declines in total fertility. Context effects largely dominate individual constraints and play an important role in the occurrence of later births.

scholarly journals Schizophrenia risk and reproductive success: A Mendelian randomization study

2018 ◽  
Author(s):  
Rebecca B Lawn ◽  
Hannah M Sallis ◽  
Amy E Taylor ◽  
Robyn E Wootton ◽  
George Davey Smith ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Mendelian Randomization ◽  
Causal Effect ◽  
Age At First Birth ◽  
First Birth ◽  
Genetic Liability ◽  
Number Of Children ◽  
Log Odds ◽  
Using Data ◽  
Robust Evidence

SummarySchizophrenia is a debilitating and heritable mental disorder associated with lower reproductive success. However, the prevalence of schizophrenia is stable over populations and time, resulting in an evolutionary puzzle: how is schizophrenia maintained in the population given its apparent fitness costs? One possibility is that increased genetic liability for schizophrenia, in the absence of the disorder itself, may confer some reproductive advantage. We assessed the correlation and causal effect of genetic liability for schizophrenia with number of children and age at first birth using data from the Psychiatric Genomics Consortium and UK Biobank. Linkage disequilibrium score regression showed little evidence of genetic correlation between genetic liability for schizophrenia and number of children (rg=0.002, p=0.84) or age at first birth (rg=-0.007, p=0.45). Mendelian randomization indicated no robust evidence of a causal effect of genetic liability for schizophrenia on number of children (mean difference: 0.003 increase in number of children per doubling in the natural log odds ratio of schizophrenia risk, 95% CI: −0.003 to 0.009, p=0.39) or age at first birth (−0.004 years lower age at first birth, 95% CI: −0.043 to 0.034, p=0.82). These results suggest that increased genetic liability for schizophrenia does not confer a reproductive advantage.

Marital Fertility and the Family in Poland from the Late Nineteenth to the Early Twentieth Century

2018 ◽  
Vol 49 (2) ◽  
pp. 279-303 ◽  
Author(s):  
Grażyna Liczbińska ◽  
Ewa Syska ◽  
Renata Koziarska-Kasperczyk ◽  
Anna Kledzik
Keyword(s):  
Twentieth Century ◽  
Marital Fertility ◽  
Age At First Birth ◽  
First Birth ◽  
Number Of Children ◽  
Age At Marriage ◽  
Early Twentieth Century ◽  
First Child ◽  
The Family ◽  
Late Nineteenth

Research in the obscure domicile files of Poznań’s Municipal Records reveals that in late nineteenth- and early twentieth-century Poznań, fertility was determined by the interaction of many socioeconomic factors. Mothers’ birth cohort and husbands’ socioeconomic status proved to be the strongest factors significantly influencing women’s age at matrimony, their age at first birth, and their number of children. Women born before 1890 married and started giving birth to the first child later than those born after 1890. The wives of workers and craftsmen started reproduction earlier and had more children than those of white-collar professionals. Religion did not influence women’s age at marriage and age at first birth, but it did influence their number of children.

Covariates of age at first birth in Guyana: a hazards model analysis

1987 ◽  
Vol 19 (4) ◽  
pp. 427-438 ◽  
Author(s):  
K. Vaninadha Rao ◽  
Komanduri S. Murty
Keyword(s):  
Fertility Survey ◽  
Age At First Birth ◽  
Birth Cohorts ◽  
Urban Residence ◽  
First Birth ◽  
Number Of Children ◽  
Early Entry ◽  
Hazards Model ◽  
First Birth Timing

SummaryAnalysis of data from the Guyana Fertility Survey on the trends and covariates of age at first birth among various birth cohorts of women ever in union indicates that an early entry into union is associated with young age at first birth and higher number of children born. Multivariate analysis showed that women with highér education, urban residence, and entry into union at age 20 or older among younger cohorts experienced lower risks for first birth compared to others, and that young women are delaying their first birth for longer durations than older women. Work status of women before first birth and the starting age of union seem to be the two major contributory factors for age at first birth. Noticeably, the role of education has changed and is now more significant among younger cohorts than among older ones for first birth timing.

scholarly journals Utilization of free maternity services among mothers aged 18-49 years in Nakuru County, Kenya

2021 ◽  
Vol 9 (1) ◽  
pp. 83
Author(s):  
Priscilla J. Najoli ◽  
Joyce Kirui ◽  
Grace Wanjau ◽  
George Otieno ◽  
Alison Yoos ◽  
...  
Keyword(s):  
Household Income ◽  
Qualitative Data ◽  
Care Facility ◽  
Residential Area ◽  
Average Score ◽  
Age At First Birth ◽  
Sources Of Information ◽  
First Birth ◽  
Maternity Services ◽  
Number Of Children

Background: In Kenya, the hope of free maternity services (FMS) is to increase the demand for maternity health care services offered by certified health professionals. Thus, this study aimed to determine and understand the utilization level of FMS among mothers aged 18-49 years living in Naivasha Sub-County, Kenya.Methods: A mixed-methods approach collected quantitative and qualitative data through structured questionnaires, health records reviews, focus group discussions, and key informant interviews. The quantitative and qualitative data were analyzed by use of Statistical package for social sciences (SPSS) 20 and content analysis, respectively. The quantitative data results were further subjected to multiple regression analysis.Results: The findings showed that over 80% utilized antenatal care, facility deliveries and postnatal care, but 68% of respondents used family planning. The mothers were found active in their first, second and third pregnancies in utilizing FMS, followed by a sudden decline. The mothers preferred the public health facilities to the private, mission and Non-Governmental Organizations (NGOs). The significant findings influencing the utilization of FMS among the mothers were age (p=0.004), the number of children (p=0.000), age at first birth (p=0.025), household income (p=0.008) and residential area (p=000). The mothers' level of knowledge on FMS had an average score of 80%, obtained by use of the Linkert scale. The radio, television, health facility and community sources were significant with (p=0.000).Conclusions: The decision-makers consider age, the number of children, age at first birth, household income and residential area in the formulation of FMS policies. Further, utilize relevant sources of information on FMS in the community.   

scholarly journals Mega-analysis of 31,396 individuals from 6 countries uncovers strong gene-environment interaction for human fertility

2016 ◽  
Author(s):  
Felix C. Tropf ◽  
Renske M. Verweij ◽  
Peter J. van der Most ◽  
Gert Stulp ◽  
Andrew Bakshi ◽  
...  
Keyword(s):  
Individual Differences ◽  
Twin Studies ◽  
Genetic Effects ◽  
Age At First Birth ◽  
Environment Interaction ◽  
First Birth ◽  
Time And Space ◽  
Number Of Children ◽  
Human Fertility ◽  
Gene Environment

AbstractFamily and twin studies suggest that up to 50% of individual differences in human fertility within a population might be heritable. However, it remains unclear whether the genes associated with fertility outcomes such as number of children ever born (NEB) or age at first birth (AFB) are the same across geographical and historical environments. By not taking this into account, previous genetic studies implicitly assumed that the genetic effects are constant across time and space. We conduct a mega-analysis applying whole genome methods on 31,396 unrelated men and women from six Western countries. Across all individuals and environments, common single-nucleotide polymorphisms (SNPs) explained only ~4% of the variance in NEB and AFB. We then extend these models to test whether genetic effects are shared across different environments or unique to them. For individuals belonging to the same population and demographic cohort (born before or after the 20th century fertility decline), SNP-based heritability was almost five times higher at 22% for NEB and 19% for AFB. We also found no evidence suggesting that genetic effects on fertility are shared across time and space. Our findings imply that the environment strongly modifies genetic effects on the tempo and quantum of fertility, that currently ongoing natural selection is heterogeneous across environments, and that gene-environment interactions may partly account for missing heritability in fertility. Future research needs to combine efforts from genetic research and from the social sciences to better understand human fertility.Authors SummaryFertility behavior – such as age at first birth and number of children – varies strongly across historical time and geographical space. Yet, family and twin studies, which suggest that up to 50% of individual differences in fertility are heritable, implicitly assume that the genes important for fertility are the same across both time and space. Using molecular genetic data (SNPs) from over 30,000 unrelated individuals from six different countries, we show that different genes influence fertility in different time periods and different countries, and that the genetic effects consistently related to fertility are presumably small. The fact that genetic effects on fertility appear not to be universal could have tremendous implications for research in the area of reproductive medicine, social science and evolutionary biology alike.

scholarly journals Evaluating the Role of Education as a Birth Control Policy in Burkina Faso: A Propensity Score Weighting Approach

2018 ◽  
Vol 11 (9) ◽  
pp. 36
Author(s):  
David Aimé Zoundi ◽  
Jean-Louis Bago ◽  
Wamadini dite Minata Souratié ◽  
Miaba Louise Lompo
Keyword(s):  
Propensity Score ◽  
Burkina Faso ◽  
Birth Control ◽  
Causal Effect ◽  
Individual Characteristics ◽  
Demographic And Health Surveys ◽  
Age At First Birth ◽  
First Birth ◽  
Propensity Score Weighting ◽  
Number Of Children

We use the 2014 round of Burkina Faso’s Demographic and Health Surveys (DHS) to identify and quantify the causal effect of women’s education on their fertility outcomes focusing on two fertility indicators: the total number of children ever born and the age at first birth. However, women's educational attainments may reflect the difference in term of access to schooling or individual characteristics such the family wealth, causing a threat to the empirical identification. In order to achieve consistent estimation, our empirical strategy follows Imbens (2000) and uses the propensity score weighting (PSW) approach to generate an appropriate counterfactual group accounting for education levels. Results from the PSW estimation suggest that education reduces the number of children per woman and delays women’s first birth in Burkina Faso. Hence, promoting girls education is an efficient policy to achieve birth control in Burkina Faso.

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