Age-specific Fertility Research Articles

Change-point detection in functional time series: applications to age-specific mortality and fertility

Change-point detection in functional time series: applications to age-specific mortality and fertility

Fertility model evolution: A survey on mathematical models of age-specific fertility with application to Nepalese and Malaysian data

Fertility pattern analysis and modeling to smooth age-specific fertility rates (ASFRs) form a well-established research field that holds particular importance for Asian countries. In developed nations, ASFRs typically display a bimodal skewed fertility curve, whereas, in developing countries, they usually exhibit a unimodal skewed fertility curve that diverges from the normal one. For decades, demographic experts worldwide have been interested in creating models using deterministic and stochastic approaches to represent these fertility curves. In this regard, parametric and non-parametric models have been created, with the latter providing a better fit for ASFR data. This research investigates the evolution of fertility models aimed at smoothing ASFRs. It explores suitable alternative models for countries with fast-declining, unimodal, and skewed fertility curves of ASFRs, such as Nepal and Malaysia. Nepal’s fertility rate is transitioning from a high level toward the replacement rate (2.1) at the year 2021; meanwhile, Malaysia’s fertility rate (1.7) in the year 2021 has dropped below the replacement rate. Given the lack of a universally applicable model for ASFR pattern variation, this study proposes the Kumaraswamy log-logistic distribution as a promising model to represent the ASFRs of Nepal and Malaysia accurately. Various approaches, including the Akaike information criterion, and Bayesian information criterion, are employed to validate the fitting of the proposed model.

Modelling the age pattern of fertility: an individual-level approach.

Fitting statistical models to aggregate data is still the dominant approach in many demographic and biodemographic applications. Although these macro-level models have proven useful for a variety of tasks, they often have no demographic interpretation. Individual-level modelling, on the other hand, offers a deeper understanding of the mechanisms underlying observed patterns. Their parameters represent quantities in the real world, instead of pure mathematical abstractions. However, estimating these parameters using real-world data has remained a challenge. The approach we introduce in this article attempts to overcome this limitation. Using a likelihood-free inference technique, we show that it is possible to estimate the parameters of a simple but demographically interpretable individual-level model of the reproductive process by exclusively relying on the information contained in a set of age-specific fertility rates. By estimating individual-level models from widely available aggregate data, this approach can contribute to a better understanding of reproductive behaviour and its driving mechanisms, bridging the gap between individual-level and population-level processes. We illustrate our approach using data from three natural fertility populations.

Mapping fertility rates at national, sub-national, and local levels in Ethiopia between 2000 and 2019.

Fertility rates are key indicators of population health and demographic change, influencing economic development, healthcare planning, and social policies. Understanding subnational variation in fertility rate is important for effective geographical targeting and policy prioritization. This study aimed to identify geographic variation, trends, and determinants of fertility rates in Ethiopia over the past two decades. We estimated total fertility rates (TFRs) and age-specific fertility rates (ASFRs) using five nationally representative cross-sectional Demographic and Health Surveys collected in Ethiopia between 2000 and 2019. ASFRs represent the number of live births per 1,000 women aged 15 to 49 during the 3 years before each survey, while TFRs indicate the average number of children a woman would have by the end of her reproductive years, calculated as the sum of ASFRs over five-year intervals. We developed model-based geostatistics by incorporating demographic and healthcare access data with spatial random fields to produce high-resolution fertility rate maps. These results were then aggregated to produce fertility rate estimates at local, sub-national, and national levels in Ethiopia. The national TFR gradually declined from 4.8 live births in 2000 to 4.2 live births in 2019, but it is still above the replacement level of 2.1 children per woman. There were sub-national and local variations in TFR, ranging from 5.7 live births in Somalia and 5.3 Oromia regions to 2.7 live births in Addis Ababa and 3.6 live births Dire Dawa cities. Geographical areas with high TFR were mostly associated with a high proportion of Muslim women and low access to health facilities. Despite a decline in fertility rates among women of reproductive age over the past two decades, marked spatial variation persists at sub-national and local levels in Ethiopia, with demographic factors determining the spatial distribution and rate of decline, highlighting the need for tailored programs and strategies in high-fertility areas to increase access to family planning.

Trends and risk indicators for high fertility among Nigerian female youth aged 15–29 years: A pooled data analysis

IntroductionNigeria's age-specific fertility rates are highest among the country's youth population, yet little is known about the factors that influence female youth fertility in Nigeria. This study examined fertility trends and risk factors associated with high fertility among Nigerian female youth aged 15 to 29. MethodsWe examined a pooled data from four rounds of the Nigeria Demographic and Health Surveys (conducted in 2003, 2008, 2013, and 2018). Of the data, 62,713 female youth were extracted for this study. Descriptive statistics and multinomial logistic regression were employed. ResultsThe results show that 21.5 % of the sample had 3 or more children. Between 2003 and 2018, there was a drop of only 28 live births per 1000 women among the youth. Female youth with less than a secondary education were twice as likely to have 1–2 children (adjusted odds ratio [aOR] = 1.54, 95 % confidence interval [CI] = 1.43–1.66) and three times as likely to have 3 or more children (aOR = 3.32, 95 % CI = 3.03–3.64) compared to those with a secondary education or higher. Unmarried female youth were 95 % less likely to have 1–2 children and 98 % less likely to have 3 or more children. Additionally, female youth from the lowest-income families were twice as likely to have 1–2 children (aOR = 2.06, 95 % CI = 1.84–1.84) and four times as likely to have 3 or more children (aOR = 3.50, 95 % CI = 3.03–4.05) compared to those from the highest-income families. ConclusionTo control high fertility, significant improvement in education, employment, ending early marriage, poverty and unfavorable pronatalist cultural norms, are required.

Exploring Fertility Dynamics and Factors Shaping Russia’s Demographic Prospects

The research examines fertility patterns in Russia by using current calendar birth rates and their implications for actual generations. Birth rates for these generations are derived from the 2020 Census data and are further refined through calculations employing one-year age-specific rates. This methodology allows us to estimate parameters for age-specific fertility models in real generations, offering a different approach compared to traditional population census methods. Given the variance in fertility rates by birth order, the analysis favors a segmented approach, separately considering trends for first, second, third, and subsequent births. Factors influencing fertility are examined both statistically, with a focus on the impact of population age–sex structure transformations on overall fertility rates, and through insights from Vyborochnoe nabliudenie reproduktivnykh planov naseleniia [Sample Observation of Population Reproductive Plans] performed by Rosstat [Federal State Statistics Service] in 2022. Value orientations are the primary determinant in reproductive behavior, which means that a key goal of demographic policy is to influence these orientations. However, it is also possible to influence fertility rates through social and demographic policies creating favorable conditions for families to fulfill their desire for children.

O-105 Contribution of ART to fertility rates and family size

Abstract In the last three decades declining fertility has become an increasing global trend. One-half of the global population today lives in countries where the period Total Fertility Rate is below 2.1 births per woman. Many countries in Europe and Asia are experiencing “ultra-low” fertility rates of 1.0-1.4 births per woman. This decline in births creates both social and economic challenges. In addition, most countries have gone through a long period of increasing average age at birth. The shift in births at older ages has been accompanied by a concomitant decline in completed family size. As the average age at having children has increased over time, the proportion of women experiencing difficulty in achieving a pregnancy has also increased, with assisted reproductive technology (ART) treatments becoming increasingly important in counteracting this decline. However, the demographic impact of ART widely varies across countries, with the proportion of babies born as a result of ART, ranging from almost 10% of birth in in some European countries to < 1% in Latin America and 2% in the USA. ART is increasingly being raised as a potential policy tool to increase fertility. While ART can broaden the range of possible responses to low fertility rates, there are a number of challenges in quantifying contribution to fertility rates. There are also a number of important unintended consequences that need to be taken into account when trying to estimate their effectiveness as a policy tool to increase fertility. In this presentation, the evidence for the contribution of ART to total and age-specific fertility rates in different settings will be summarized and compared with other pronatalist policies. The contribution of ART and other forms of fertility treatment to completed family size and childbearing timing will also be described and discussed. Assisted reproduction is making a modest and increasing contribution to the fertility rate of high-income countries, but its potential impact should not be overestimated.

Concurrent decline in teenage fertility rate and binge drinking? An observational study across 45 nations.

Alcohol consumption is associated with unintended pregnancies among teenagers. Its role as a broader determinant of teenage fertility rates remains unclear. We investigate whether adolescent binge drinking affects the number of teenage births. Binge drinking data from 137,898 females aged 15-16 were collected in the HBSC study (2002-2018, 43 countries/regions) and 267,359 in the ESPAD study (1995-2019, 41 countries/regions). Age-specific fertility rates were from the Human Fertility Database and the World Health Organization. We examined changes over time in countries' average levels of binge drinking among female pupils aged 15-16 and population-level fertility rates for the same cohorts when aged 16-19 years. Controlling for differences between countries and survey waves, we found an association between binge drinking and fertility rate, B = 0.019, 95% confidence interval [0.004, 0.034]. When accounting for the countries' time trends, the association was substantially reduced, B = 0.006, 95% confidence interval [-0.0062, 0.0174]. The relationship was not moderated by abortion rates and controlling for contraceptive use had no impact on the findings. The association between adolescent binge drinking and fertility rates diminishes when accounting for country-specific time trends. Given the lack of clear mechanisms linking binge drinking to trends in fertility rates rather than shorter-term changes, the association likely reflects broader secular trends. Binge drinking may be involved in teen pregnancy and childbirth in individual cases but it does not explain recent developments in teenage fertility rates.

Predictions of Malaysia Age-Specific Fertility Rates using the Lee-Carter and the Functional Data Approaches

Global fertility has been experiencing a significant decline, reaching towards the replacement ratio. This trend, coupled with increasing life expectancies, has led to the emergence of an ageing population. In this study, we delve into an analysis of fertility patterns among Malaysian women, considering both their childbearing age and ethnic groups. A comprehensive 63-year fertility dataset, from 1958 to 2020, were obtained from the Department of Statistics Malaysia. These data were fitted into the Lee-Carter model and its modified version, which is the functional data model. The models were evaluated using the out-sample forecast error measures. Results indicate that the third-order functional data model able to capture most of variation present in the actual data, consequently outperforming the Lee-Carter model in forecasting fertility rates among Chinese and Indian populations. The 20-year forecasts reveal a noteworthy shift in maternal ages of the highest births to older ages suggesting a trend towards delayed pregnancies among women. It is predicted that the Malay total fertility rates will likely fall to below the replacement level reaching 1.71 in 2040 whereas Chinese and Indian total fertility rates will substantially decrease to the lowest level in history below 1.0 which are 0.54 and 0.70 respectively. The evolution in Malaysian fertility rates is an alarming fact as, together with low mortality rates, it may impact the Malaysian population structure in future. Proactive policy measures are urgently needed to address these demographic shifts.

Structural and Timing Transformations of Fertility ‒ Threats to Demographic Security of the Republic of Tatarstan

Introduction. The relevance of the article is determined by the importance of assessing the determinants of fertility to determine the possible prospects for its change and the correct justification of the directions and measures of demographic policy aimed at increasing it. The aim of the study is to identify the determinants of fertility decline in the Republic of Tatarstan in 2020‒2022 in comparison with the pre-pandemic period and to predict their impact. Materials and Methods. The authors have calculated and analyzed the dynamics of age-specific fertility rates in the Republic of Tatarstan. The influence of the structural factor and the factor of birth intensity, as well as the indirect factor ‒ age-specific marriage rates ‒ was estimated. Using the method of age movement, the dynamics of fertility and the impact of these factors on it up to 2042 were forecasted. Results. The decrease in the total fertility rate in the Republic of Tatarstan in 2020‒2022 was due to changes in the sex and age structure of the population. The excess of the total fertility rate of the region over the indicators of the Volga Federal District and the Russian Federation is due to higher total coefficients for first and second births. The difference between the average number of first births for real generations and for calendar years is determined by temporal shifts associated with postponement of first births due to late entry into first marriage and registered marriages. Discussion and Conclusion. It is predicted that the number of young people will decrease until 2028 and the number of births until 2031. The negative impact of the factor of the gender and age structure of the population will last until 2030, in the 2030s the structural factor will contribute to an increase in the overall fertility rate. The research results presented in the article can be used to determine hypotheses regarding fertility prospects when developing forecasts for demographic and socio-economic development. Correct assessment of the determinants of fertility provides grounds for the development of effective measures of demographic policy with regard to fertility.

Repercussions of the Recent Economic Downturn on Birth Rates in Greece

A comprehensive analysis of historical economic recessions in developed nations confirms the significant impact of social and economic crises on fertility rates. Across different countries, these effects exhibit common characteristics, such as a modest influence on overall fertility rates, delays in the timing of first childbirth linked to later marriages or unions, and a correlation between unemployment and age-specific fertility. Countries with established family policies and robust social security systems tend to experience less pronounced changes in fertility behavior during economic crises. The recent economic downturn in Greece unfolded amidst unique social conditions, including increased female labor force participation, widespread use of reliable contraception allowing for delayed childbearing, and escalating social security and healthcare costs due to an aging population. These factors may influence reproductive decisions and exacerbate the adverse effects of the recession on fertility rates. This study utilizes the latest official data from Greece to examine the impact of the current economic crisis on fertility levels and their evolution over time.

A novel approach for estimating fertility rates in finite populations using count regression models

Demographic health surveys (DHS) contain in-depth information about the demographic characteristics and the factors affecting them. However, fertility rates which are the important indicators of population growth have been estimated by utilizing the design-based approaches. Model-based approach, on the other hand, facilitates efficient predictive estimates for these rates by utilizing the demographic and other family planning related characters. In this article, we first attempt to observe the effect of various socio-demographic and family planing related factors on births counts by fitting different regression models to Pakistan Demographic Health Survey 2017–2018 data under classical as well as Bayesian frameworks. The births occurred during the time periods of 1-year, 3-years and 5-years are taken as the responses and modeled using different non-linear models. The model-based approach is then used for estimation of the fertility measures including age-specific fertility rates, total fertility rate, general fertility rate, and gross reproduction rate for ever-married women in Pakistan. The performance of the model-based estimators is examined using a bootstrapped sampling algorithm. While the age-specific fertility rates are over-estimated for some age groups and under-estimated for others. The model-based fertility estimates are recommended for estimating the demographic indicators at national and sub-national levels when survey data contains incomplete or missing responses.

On fertility of female population of large-scale industrial agglomeration of cities of the Irkutsk Oblast

The article considers the most important demographic indicator of natural movement of population - the natality. The dynamics of age-specific fertility of female population residing industrial highly urbanized areas of the region is demonstrated. The increase of total fertility was established. The dynamics of common and standardized coefficients of age-specific fertility of female population revealed process of aging (motherhood). However, the cleared, accurate net-coefficient of population reproduction indicates that positive dynamics of general, age-specific fertility ensures only simple character of population reproduction in city of Angarsk. The population of cities of Irkutsk and Shelekhov remains in narrowed character of population reproduction. The special coefficients of fertility make it possible to obtain accurate age-specific qualitative characteristic of fertility of female population and to forecast demographic situation in the region.

Возрастная структура рождаемости городского и сельского населения в постсоветской России: региональные тренды, основанные на панельных данных

The age model of fertility in post-Soviet Russia is constantly changing. The general trend here is an increase in the average age of motherhood, but age-related fertility patterns are subject to spatial and temporal differentiation. The study, based on a panel regression analysis of time trends, determined the average rate of change in age-specific fertility rates for the most important 5-year age groups of women living in urban and rural areas, in a spatial and temporal context for 79 regions in 1993–2022. It has been established that the transition to the age structure of fertility characteristic of developed countries, when the postponement of childbearing at a young age is compensated by its increase in maturity, in post-Soviet Russia is valid only for the urban population, while rural population does not have such compensation. Regardless of the grouping of regions, age, intertemporal and rural- urban differences in the dynamics of fertility were revealed. Regional peculiarities of women’s reproductive behavior have been identified, which are consistently reproduced in several age groups and time periods

ANALISIS UMUR REPRODUKSI PALING AWAL DAN PALING AKHIR SERTA PUNCAK FERTILITAS PADA WANITA DI SETIAP KABUPATEN DAN KOTA DI PROVINSI BANTEN

The birth rate (fertility) is one of the factors that influences the increase in population. Banten Province has 8 districts and cities with different fertility rates. One of the fertility indicators presented in the Long Form SP2020 data is Birth Rate data by Age Group / Age Specific Fertility Rate (ASFR). The aim of this research is to determine the earliest, latest reproductive age and the age of women who have the highest fertility rates in each district and city in Banten Province. The skewness (measure of slope) and kurtosis (measure of sharpness) values of the continuous curve formed will also be studied. ASFR data presented by the Central Statistics Agency (BPS) is discrete data. Fertility rates will be approached using the MBF (Modified Beta Function) continuous fertility model. In this research, information was obtained that the earliest reproductive age in Banten Province was 15.64 years. This happened to women in Lebak Regency. Meanwhile, the latest reproductive age in Banten Province is 49.85 years. This happened to women in Pandeglang Regency. It can also be seen that the highest peak fertility rate for the population of Banten Province occurred in women aged 27.54 years in the Cilegon City area, with a peak fertility value of 0.13055. Apart from being based on calculations, this is in accordance with the curve visualization carried out using Mathematica software. The highest skewness value occurs in the continuous fertility curve for the Lebak Regency area. This means that Lebak Regency has the most left-leaning curve. All continuous fertility curves in districts and cities in Banten Province have a platykurtic distribution (flat curve) because the kurtosis value is smaller than 0.263

Stochastic Forecasting of Regional Age-Specific Fertility Rates: An Outlook for German NUTS-3 Regions

Regional fertility forecasts are important for long-term planning in a variety of fields that include future birth numbers in their forecast, such as school or kindergarten planning. They are one of the major components of regional population forecasts as well. Therefore, it is important to construct reliable forecasts that are based on sophisticated models that cover the high complexity of future regional fertility. We suggest a novel forecast model for forecasting regional age-specific fertility rates that covers long-term trends by time series models, demographic and regional correlations by principal component analysis, and future uncertainty by Monte Carlo simulation. The model is applied to all German NUTS-3 regions (districts/Kreise) simultaneously, where we forecast all regional age-specific fertility rates through the period of 2022–2045. The results from the simulations are presented via median predictions with 75% prediction intervals of the regional total fertility rates. The simulation shows strong regional heterogeneities in long-term fertility trends that are associated with the historical background of Germany, housing supply for families, opportunities for education, and the strength of labor markets, inter alia.

Age-period-cohort analysis of U.S. fertility: a realistic approach

A key question for the explanation of fertility trends in advanced societies is whether, in addition to age, period- rather than cohort-related factors matter. In this paper, we analyze a standard set of age-specific fertility rates – from the Human Fertility Database – on the United States between 1933 and 2015. More specifically, we describe and apply an Age-Period-Cohort (APC) modeling approach that relies on second differences as identifiable parameters. Results of our APC analyses tend to be consistent with an interpretation that gives a greater weight to period effects over shorter time horizons, with a significant presence of smooth cohort effects over the longer term.

Analysis of age-specific fertility in India: Deterministic and non-deterministic modeling approaches

The main objective of this study is to investigate the pattern of age-specific fertility rates (ASFRs) in India using deterministic and non-deterministic approaches. Toward this end, we proposed statistical polynomial regression models to study the distributional pattern of ASFRs for total, rural, and urban women in India. Further, a comparative study considering selected skewed regression models was undertaken. For this study, secondary data on ASFR were collected from Sample Registration System, Statistical Report-2020, and from National Family Health Survey 5 (NFHS-5; 2019 – 2021). It was found that all three subcategories of ASFRs, namely, the total, rural, and urban ASFRs, followed the reciprocal biquadratic polynomial model. On the other hand, all three subcategories of ASFR follow the skew-normal type 2 distribution. Similar findings were also obtained and validated based on NFHS-5 data. Further, the chosen statistical models’ validity and stability were tested using various model validation techniques and model selection criteria.

A Bayesian model for the reconstruction of education- and age-specific fertility rates: An application to African and Latin American countries

A Bayesian model for the reconstruction of education- and age-specific fertility rates: An application to African and Latin American countries

A Polynomial-Based Mathematical Modelling of Age-Specific Fertility and Marital Fertility Rates of Assam

A Polynomial-Based Mathematical Modelling of Age-Specific Fertility and Marital Fertility Rates of Assam