Age-specific Fertility Research Articles

General and age-specific fertility rates in non-affective psychosis: population-based analysis of Scottish women

PurposeWomen diagnosed with non-affective psychosis have a lower general fertility rate (GFR) and age-specific fertility rate (ASFR) than women in the general population. Contemporary data on GFR in this group remain limited, despite substantive changes in prescribing and management. We calculated contemporary estimates of the GFR and ASFR for women diagnosed with non-affective psychosis compared with the general population of women without this diagnosis.MethodsA population-based design combined routinely collected historical maternity and psychiatric data from two representative areas of Scotland. Women were included from the NHS Grampian or Greater Glasgow and Clyde areas and were aged 15–44 between 2005 and 2013 inclusive. The ‘exposed’ group had a diagnosis of non-affective psychosis (ICD-10 F20–F29) and was compared to the general population of 'unexposed' women in the same geographical areas.ResultsAnnual GFR between 2005 and 2013 for women with non-affective psychosis varied from 9.6 to 21.3 live births/1000 women per year in the exposed cohort and 52.7 to 57.8 live births/1000 women per year in the unexposed cohort, a rate ratio (RR) of 0.28 [p < 0.001; 95% CI (0.24, 0.32)]. ASFR for all 5-year age groups was lower in the exposed cohort than amongst unexposed women.ConclusionWe highlight continued low fertility rates in women with a diagnosis of non-affective psychosis, despite widespread availability of prolactin-sparing atypical antipsychotics. Accurate estimation of fertility rates remains crucial in developing needs-matched perinatal care for these women. Methodological improvements using routine datasets to investigate perinatal mental health are also urgently needed.

Staying alive enhances both women's and men's fitness.

We argue that Benenson et al. need to consider not only sex differences in the effects of care on offspring survival but also in age-specific fertility when predicting how longevity affects fitness. We review evidence that staying alive has important effects on both women's and men's fitness, and encourage consideration of alternative explanations for observed sex differences in threat responses.

Սոցիալական ծրագրերի գրավչությունը և ծնելիության մակարդակի վայրիվերումները ՀՀ-ում/Attractiveness of Social Programs and Birth Rate Fluctuation in the Republic of Armenia

Since the end of the 20th century, the world has registered a decline in the global fertility rate. According to UN forecasts, the fertility decline rate in the world will continue up to mid 21st century and by 2045-2050 the average number of births to a woman of reproductive age will be 2.2, and in 2100- 1.9. Consequently, many countries around the world have adopted measures to promote the birth rate. In almost all the countries, including the Republic of Armenia, the socio-demographic policies of birth promotion is mainly implemented through two methods: legally defined vacations and benefits. In the mid-20th century, the fertility rate (the average number of children a woman would bear in her lifetime if she experienced the current age-specific fertility rates throughout her reproductive years) in Armenia decreased from 4.7 births, and in 2020 it was already at 1.66. During the observed period, the decline in the reproduction rate was registered in the country, this was also negatively impacted by poverty, emigration, high unemployment, the Artsakh war and the pandemic. If the birth rate continues to decline, Armenia will be in a much more dangerous position in the near future, as the population of reproductive age will continue to decline, which, in turn, will lead to a decrease in the reproductive capacity of the population. The paper addresses the reasons, measures taken to improve and their impact on the decline of the birth rate both in Armenia and in a number of foreign countries.

Postdiapause reproduction of spotted-wing drosophila (Diptera: Drosophilidae) in realistically simulated cold climatic springtime conditions of Québec, Canada

Abstract Knowing the biology and ecology of Drosophila suzukii (Diptera: Drosophilidae) is important to predict its potential for permanent establishment in cold climatic regions. We studied the reproductive potential of postdiapause male and female flies collected in lowbush blueberry fields in late season over two years. After being submitted to a six-month cold-winter regime, survivors were exposed to a simulated springtime warming regime to monitor reproductive potential and expected population growth. Overwintered fly survivors of both sexes that were aged up to nine months after field capture reproduced successfully in spring and early summer when mated to nondiapause flies experimentally made available for mating as potential migrant colonisers from lower latitudes. Relative to control nondiapause flies, the lifetime fertility of postdiapause flies was reduced by 84% in females and 70% in males, revealing large fitness costs of reproductive diapause under cold stress. Modelling potential reproduction of overwintered flies in warming conditions using models parametrised for age-dependent fertility rate and diapause status showed that nondiapause migrant flies would be strongly advantaged over locally overwintered postdiapause flies due to precocious reproductive maturity, broader pattern of age-specific fertility, and higher lifetime fertility.

Fertility Situation among Urban and Rural Residents in Indonesia; Based on Indonesian Census 2010

Indonesia is a large country with a big share of the world’s population. The fertility rate can vary in different areas caused of some factors, including culture, socioeconomic status, education, social support, etc. This research analyzed the census data in 2010, examining the fertility rate differential in urban and rural areas in Indonesia using the Brass method. The method estimated indirect estimation of the fertility rate, including adjusted age-specific fertility rate (ASFR), adjusted total fertility, and adjusted birth rate. The descriptive analysis explained the fertility situation in Indonesia’s urban and rural areas. The result revealed that the adjusted ASFR in urban areas was higher than in rural areas when women were aged 25-39, while in the rural areas, the adjusted ASFR was higher than in the urban area when women were aged 15-24. The estimated number of birth have a similar pattern with adjusted ASFR. Rural regions have higher total fertility, birth rate, and general fertility rates than urban residents. Marriage status and contraceptive use impact fertility differences between urban and rural areas. In conclusion, rural areas had a higher fertility rate than urban areas based on the Indonesian census 2010.

Cohort consequences of drought and family disruption for male and female African elephants

Abstract Cohort effects, reflecting early adversity or advantage, have persisting consequences for growth, reproductive onset, longevity, and lifetime reproductive success. In species with prolonged life histories, cohort effects may establish variation in age-sex structures, while social structure may buffer individuals against early adversity. Using periods of significant ecological adversity, we examined cohort effects for male and female elephants (Loxodonta africana) over almost 50 years in Amboseli, Kenya. Mortality spiked during severe droughts with highest mortality among calves under 2 years and females over 40 years. Deaths of oldest females resulted in social disruption via matriarch turnover, with potential impacts on resource acquisition for survivors. We predicted that survivors of high mortality and social challenges would have altered life-history trajectories, with later age at first reproduction and reduced age-specific fertility for females and slow transitions to independence and late-onset of potential mating or musth among males. Contrary to expectations, there were no persisting early drought effects on female age at first conception while matriarch loss around puberty accelerated reproductive onset. Experience of an early life drought did not influence age-specific reproductive rates once females commenced reproduction. Males who survived an early drought exhibited complex consequences: male age at family independence was later with larger peer cohort size, but earlier with drought in year of independence (13.9 vs 14.6 years). Early drought had no effect on age at first musth, but male reproductive onset was weakly associated with the number of peers (negative) and age at independence (positive).

Geographic Variation in Personality is Associated With Fertility Across the United States.

Levels of fertility and the shape of the age-specific fertility schedule vary substantially across U.S. regions with some states having peak fertility relatively early and others relatively late. Structural institutions or economic factors partly explain these heterogeneous patterns, but regional differences in personality might also contribute to regional differences in fertility. Here, we evaluated whether variation in extraversion, agreeableness, conscientiousness, neuroticism, and openness to experience measured at the U.S. state-level was associated with the level, timing, and context of fertility across states above and beyond sociodemographics, voting behavior, and religiosity. Generally, states with higher levels of agreeableness and conscientiousness had more traditional fertility patterns, and states with higher levels of neuroticism and openness had more nontraditional fertility patterns, even after controlling for established correlates of fertility (r ~ |.50|). Personality is an overlooked correlate that can be leveraged to understand the existence and persistence of fertility differentials.

Subnational spatial variations of fertility timing in Europe since 1990

Compared with European fertility trends, little is known on the spatial variations of fertility timing. This is particularly true within countries. While theories such as the Second Demographic Transition have brought good understanding to both the nature and origins of the recent changes in fertility behaviours including concerning fertility postponement, the predilection for empirical studies and cross-country analyses left the spatial organization of fertility timings relatively unrecognised. However, spatially differentiated fertility behaviours are expected theoretically. This geographical analysis presents spatial variations of fertility timing across Europe. The focus on subnational yet transnational data contribute to highlight the importance of local contexts on fertility patterns.After discussing the validity of the indicators and methods, we used mean age at birth in NUTS-2 regions and age specific fertility rates for the fine NUTS-3 spatial units to map the patterns of fertility in more than 30 countries over the 1990-2017 period. Several major results emerged. Despite general postponement of fertility to later ages in Europe resulting in a slight trend towards homogenisation, results reveal existing subnational differences. Most importantly, these differences are spatially organised. Across time the East-West divide remains a structuring contrast but other important disparities strengthen, highlighting the specificity of fertility patterns in Southern Europe and in the largest urban settlements. Eventually this inductive analysis discusses theories to explain the main spatial variations exposed. The study proves the importance to consider subnational contexts, especially metropolitan ones, when studying fertility behaviours.

Reduction in Lifetime Fertility Through MNCS in Rural Bangladesh

This study assesses the effect of a customised Maternal Neonatal and Child Survival (MNCS) intervention in the rural areas of Bangladesh. This study attempts to estimate the lifetime fertility rate and the proportion of live births ≥3, and the age-specific lifetime fertility patterns among the women of reproductive age. This quasi-experimental study used impact evaluation data from the MNCS intervention in 2013 and compared these with the baseline data collected in 2008. We used a multi-stage, cluster random sampling technique to include 6,000 and 4,800 women in 2008 and 2013, respectively. The respondents were either mothers who had alive/deceased infants or the mothers whose pregnancy was terminated or who had living children of 12–59 months without pregnancy outcomes in the preceding year of the surveys. Based on the mean difference of live births from baseline to endline year for each intervention union, and then we compared these two areas (intervention and control unions). Overall lifetime fertility rate declined significantly in high-performing intervention unions (from 2.6 to 2.2/woman, p &lt; .001) or in control unions (from 2.4 to 2.2/woman; p &lt; .001). The degree of reduction of fertility increased significantly with age, and such a change was most prominent in the case of women ≥35 years old. Multivariate analyses suggest that the likelihood of having live births ≥3 reduced significantly in high-performed intervention compared to control unions. In conclusion, the probability of reducing lifetime fertility over time increases with a higher level of access, degree and duration of the customised intervention.

Medawar and Hamilton on the selective forces in the evolution of ageing

Both Medawar and Hamilton contributed key ideas to the modern evolutionary theory of ageing. In particular, they both suggested that, in populations with overlapping generations, the force with which selection acts on traits declines with the age at which traits are expressed. This decline would eventually cause ageing to evolve. However, the biological literature diverges on the relationship between Medawar’s analysis of the force of selection and Hamilton’s. Some authors appear to believe that Hamilton perfected Medawar’s insightful, yet ultimately erroneous analysis of this force, while others see Hamilton’s analysis as a coherent development of, or the obvious complement to Medawar’s. Here, the relationship between the two analyses is revisited. Two things are argued for. First, most of Medawar’s alleged errors that Hamilton would had rectified seem not to be there. The origin of these perceived errors appears to be in a misinterpretation of Medawar’s writings. Second, the mathematics of Medawar and that of Hamilton show a significant overlap. However, different meanings are attached to the same mathematical expression. Medawar put forth an expression for the selective force on age-specific fitness. Hamilton proposed a full spectrum of selective forces each operating on age-specific fitness components, i.e. mortality and fertility. One of Hamilton’s expressions, possibly his most important, is of the same form as Medawar’s expression. But Hamilton’s selective forces on age-specific fitness components do not add up to yield Medawar’s selective force on age-specific fitness. It is concluded that Hamilton’s analysis should be considered neither as a correction to Medawar’s analysis nor as its obvious complement.

Late pregnancy: impact on prematurity and newborn's weight.

This study aimed to evaluate the frequency of late pregnancies in Brazil, the age-specific fertility rate (ASFR) in the regions, the rate of prematurity, and the rate of low birth weight (LBW) and their association with advanced maternal age compared with 20-34-year-old women. This was a cross-sectional study conducted by searching the Information System on Live Births (Sistema de Informações Sobre Nascidos Vivos [SINASC]). Data from 1995 to 2018 were collected, and pregnant women were divided into three categories based on their age range: 35-39, 40-44, and ≥45 years. The study calculated the frequency of deliveries of mothers of advanced age in Brazil, the ASFR, and the rates of prematurity and LBW in each group. The frequency of deliveries and ASFR ≥35 years increased between 1995 and 2018. The chances of prematurity and LBW were higher with increased maternal age.

Increase in fertility rate before the age of 14 in Brazil from 1996 to 2018.

This study aimed to assess live birth frequency and age-specific fertility rates (ASFR) in the period 1996-2018 and the number of pregnancies at <14 years old in the period 2012-2018. This was a cross-sectional study conducted by search on Live Births Data System (SINASC/DATASUS) database. There was a variation in ASFR in Brazil of 0.78‰ in 1996 to 0.87‰ in 2018 (+11.5%). In the north region, it increased from 1.28‰ to 1.66‰ in 2018. In the northeast region, it increased from 0.72‰ to 1.66‰ (+131%) in 1996-2011, but decreased to 1.31‰ in 2018 (-21% in relation to 2011). When comparing 1996 and 2018, in the southeast region, there was a 22% decrease; in the south region, it was 48.2%; and in the Center-West region, it was 34%; but in the north region, there was a 29.7% increase, and in the northeast region, it was 81.9%. When adding girls who became pregnant aged 13 years and gave birth at 14, there was a threefold increase in the rate. The increase of pregnancies in <14 years old in less developed regions of Brazil shows an association with socioeconomic factors and reveals the severe problem of rape of vulnerable persons in the country.

The observed pattern and hidden process of female reproductive trajectories across the life span in a non-human primate.

Age-specific fertility trajectories are fundamental to understanding population structure and the evolutionary ecology of diverse life histories. However, characterizing reproductive ageing has been difficult with cross-sectional data, where senescence especially late in life can be confounded by selective disappearance. Addressing such challenge requires longitudinal data tracking the reproductive life span of known individuals, but such data are rare, especially for very long-lived species such as primates. We analyse the entire life span trajectory of annual fertility, from reproductive maturity to death, for 673 free-ranging female rhesus macaques, Macaca mulatta, on Cayo Santiago, Puerto Rico. Using generalized linear mixed-effects models (GLMMs), we first tested if time to death explains the ageing pattern independently of and additionally to chronological age, and if so, whether there is interaction between them. While GLMM captures the patterns in the data well, it is not a generative model. For example, given the GLMM and an individual's reproductive trajectory up to a given age, we cannot directly predict the probability of reproduction or death in the next year. For this reason, we further fitted a hidden Markov chain model (HMM) which allows just such a prediction, and additionally helps infer the process underlying the observed trajectory. We show that, after accounting for individual differences in fertility, reproductive ageing exhibits both age-dependent decline and also an abrupt terminal decline independently of age at death. We infer from the HMM that the underlying process of reproductive trajectory is where individuals cycle between reproductive bouts until they enter an irreversible frail condition that constrains fertility. The findings provide valuable insights into the longitudinal progression of reproductive trajectories in primates, by revealing both age-dependent and age-independent patterns and processes of ageing, and contribute to a growing body of literature on reproductive ageing and senescence across animal taxa.

The Own-Children Method of fertility estimation: The devil is in the detail

BACKGROUND: The Own-Children Method is a widely used procedure for estimating levels, trends, and differentials in age-specific and total fertility from the age distribution. OBJECTIVE: This article demonstrates that the procedure used in most applications of the Own-Children Method produces systematically biased estimates of the age pattern of fertility and describes a new estimator that avoids this bias. METHODS: The Own-Children Method incorporates an adjustment for the proportion of children by age who are not living with their mothers. Because these children include orphans and because women’s mortality accelerates with age, this adjustment overestimates births to young women and underestimates births to older women relative to the number of women in the denominators of the fertility rates. By explicitly estimating the prevalence of maternal orphanhood by age, age-specific fertility can instead be calculated using a formula that avoids this bias. RESULTS: The bias in the estimated age pattern of fertility is trivial for rates calculated from children born in the few years before an inquiry, but increases with the age of the children and with the population’s mortality. Its overall impact is to shift the fertility distribution toward younger ages at childbearing. Because the errors for women of different ages more or less cancel each other out, the bias in estimates of total fertility is smaller. CONTRIBUTION: The new Own-Children Method estimator of age-specific fertility proposed here eliminates a small but systematic bias in the results produced by the existing procedure. It should enable analysts using the Own-Children Method to measure fertility more accurately in the future.

Forecasting the Patterns and Trends in Age-Specific Fertility in South Asia

The total fertility rate (TFR) in South Asia has decreased remarkably over the past three decades. The decline is projected to continue in the coming years mostly due to the significant changes occurring in age specific fertility rate (ASFR). This study aims to investigate ASFR trends and forecast the ASFR of India, Bangladesh, and Pakistan from 2020 to 2100. The ASFRs in South Asia data separated by 7 age groups with 5-year interval from 15 to 49 years between 1990 and 2019 were downloaded from the US Census Bureau’s website. Linear regression models were used to investigate ASFR patterns from data in that period and ASFR data in the years 2010-2019 of each age group were used to forecast the ASFRs in 2020 to 2100. The forecasted results show that ASFRs in India and Bangladesh in age group 15-24 years have steep declining trends whereas ASFRs in age group 25-29 in both countries and age group 45-49 years in India have gradually decreasing ASFR trends. Age group 30-44 years in Bangladesh have slightly decreasing ASFR trends. Pakistan with previously high fertility rates are experiencing gradually declining ASFRs in all age groups. In conclusion, the change in fertility in these three countries from low stable population to high population will occur within next 40 years from 2020

Spatio-Temporal Patterns in Portuguese Regional Fertility Rates: A Bayesian Approach for Spatial Clustering of Curves

Abstract It is important for demographic analyses and policy-making to obtain accurate models of spatial diffusion, so that policy experiments can reflect endogenous spatial spillovers appropriately. Likewise, it is important to obtain accurate estimates and forecasts of demographic variables such as age-specific fertility rates, by regions and over time, as well as the uncertainty associated with such estimation. Here, we consider Bayesian hierarchical models with separable spatio-temporal dependence structure that can be estimated by borrowing strength from neighbouring regions and all years. Further, we do not consider the adjacency structure as a given, but rather as an object of inference. For this purpose, we use the local similarity of temporal patterns by developing a spatial clustering model based on Bayesian nonparametric smoothing techniques. The Bayesian inference provides the uncertainty associated with the clustering configurations that is typically lacking in classical analyses of large data sets in which a unique clustering representation can be insufficient. The proposed model is applied to 16-year data on age-specific fertility rates observed over 28 regions in Portugal, and provides statistical inference on the number of clusters, and local scaling and shrinkage levels. The corresponding central clustering configuration is able to capture spatial diffusion that has key demographic interpretations. Importantly, the exercise aids identification of peripheral regions with poor demographic prospects and development of regional policy for such places.

Recent marriage and childbearing trends in Croatia and Slovenia: A comparative review

The paper discusses the marriage and childbearing trends in Croatia and Slovenia from 1985 to 2017. We made a comparative review of several indicators related to marriage and childbearing trends: mean ages of women at first marriage and first childbirth, birth rates, births within and outside marriage, total fertility rate, tempo-adjusted fertility rate, age-specific fertility rates, and marriage rate. The analysis is based on the official statistical data provided by the statistical offices of both countries and Human Fertility Database. Many of the indicators, including the birth rate, total fertility rate and age-specific fertility rate, are somewhat more favourable in Slovenia than in Croatia. One of the major differences between the two countries is that in Slovenia the connection between marriage and childbearing is not as nearly significant as in Croatia.

Trends on Prevalence of Teenage Pregnancy and Age-specific Fertility Rates in a Caribbean Country: A Call for Regional Intervention

Trends on Prevalence of Teenage Pregnancy and Age-specific Fertility Rates in a Caribbean Country: A Call for Regional Intervention

Fertility dynamics and reproductive behaviour of men and women entering into marriage in the Republic of Bashkortostan

The article is devoted to the analysis of the fertility rate dynamics in the Republic of Bashkortostan and the study of the reproductive behaviour of the population entering into a registered marriage. The author examines the crude and total fertility rates, the net population reproduction rate, the total fertility rate by the order of births, as well as age-specific fertility rates. In addition, basing on the data of population surveys, the author regards reproductive intentions of citizens applying for marriage in the registry office, as well as reasons that may prevent them from having a child. The study shows that the Republic of Bashkortostan is characterized by a low fertility rate; the generation of children does not replace the generation of parents. The reproductive intentions of the respondents measured by the desired and expected number of children correspond to the small (two-child) family model. Among the main reasons that can prevent the birth of a child, the first two are financial and housing difficulties, and third is the desire to live for oneself for a while.

Gender-oriented statistical discrimination: Aggregate fertility, economic sector, and earnings among young Chinese workers

Previous studies usually attribute residual gender pay gap net of human capital, job characteristics, and family responsibilities to discrimination against women, without directly exploring the underlying discriminatory mechanisms that generate gender inequalities in the labor market. By applying and extending a previously developed statistical discrimination model to post-socialist urban China, we examine the association between period age-specific fertility rate (ASFR), as a proxy for the likelihood of women taking maternity leave, and the earnings of young working women and men, as well as its variation across economic sectors. Using data compiled from a random sample of the 2005 one-percent mini-census of the People’s Republic of China, our analyses reveal gender-asymmetric associations between ASFR and earnings among young workers before their prime fertility age, where ASFR on average was negatively related to the earnings among young women, but not among young men. Moreover, such negative association was limited primarily to female workers in the private sector, negligible in state-owned and collective enterprises, and even reversed to positive among those working in government agencies and public institutions. Our findings suggest that employers in the private sector may use aggregate fertility to “evaluate” potential training and replacement costs and the productivity of female employees associated with maternity leave, thereby reinforcing and perpetuating stereotypes and discrimination against women in the workplace.