Fertility Trends Research Articles

Obesity induces male mice infertility via oxidative stress, apoptosis, and glycolysis.

The current declining trend in male fertility parallels the increasing prevalence of obesity worldwide. This paper revealed that the poor in vitro fertilization rates and decreased sperm motility in obese mice due to excessive oxidative stress enhanced apoptosis and impaired glucose metabolism in the testes. Obesity is an urgent public health problem in recent decades, linked to reduced reproductive potential, and negatively affects the success of assisted reproduction technology. The aim of this study is to investigate the mechanisms underlying impaired male fertility caused by obesity. Male C57BL/6 mice fed a high-fat diet for 20 weeks served as mouse models with moderate (20% < body fat rate (BFR) < 30%) and severe obesity (BFR > 30%). Our results showed poor in vitro fertilization rates and decreased sperm motility in obese mice. Abnormal testicular structures were identified in male mice with moderate and severe obesity. The expression level of malondialdehyde increased with obesity severity. This finding indicates that oxidative stress plays a role in male infertility caused by obesity, which was further confirmed by the decreased expression of nuclear factor erythroid 2-related factor 2, superoxide dismutase, and glutathione peroxidases. Our study also found that the expression of cleaved caspase-3 and B-cell lymphoma-2 showed an obesity severity-dependent manner indicating that apoptosis is highly correlated with male infertility caused by obesity. Moreover, the expression of glycolysis-related proteins, including glucose transporter 8, lactate dehydrogenase A, monocarboxylate transporter 2 (MCT2), and MCT4, decreased significantly in the testes of obese male mice, suggesting energy supply for spermatogenesis is impaired by obesity. Taken together, our findings provide evidence that obesity impairs male fertility through oxidative stress, apoptosis, and blockage of energy supply in the testes and suggest that male obesity influences fertility through complex and multiple mechanisms.

Parity Progression Ratio Dynamics, Determinants, and Policy Approaches: A Study in Isfahan in 2020

Background and aims: The fertility trend in Isfahan, as in other parts of the country, has decreased significantly in recent years. This study aimed to investigate the parity progression ratio (PPR) and factors affecting fertility. Methods: This is a cross-sectional study that was conducted using a researcher-made questionnaire. Moreover, the study method was a survey, and the sample size included 662 married women aged 15 to 49 years. The study also employed a multi-stage cluster sampling method. Results: The results revealed that the cumulative fertility rate ((CFR=1.5) has decreased in Isfahan. There was also a significant relationship between the number of children with abortion (P=0.001), education (P=0.000), and employment of women (P=0.02). The results of multivariate regression with the control of women’s job type also indicated that the variables of the age of marriage and literacy of women (r=0.355, P&lt;0.05) in householders, age of marriage (r=0.286, P=0.00) in unemployed, and literacy of women (r=0.336, P=0.016) in employed women have the highest explanation in childbearing. Conclusion: To increase fertility and childbearing, more attention should be paid to economic issues, inflation reduction, and employment rise so that we can witness an increase in marriage, followed by childbearing to the level of succession. The best way to maintain the level of substitution is the full and comprehensive implementation of population policies and the implementation of adaptive policies appropriate to the level of fertility.

Spatial Distribution of the Fertility Parameters in Sericulture Soil: A Case Study of Dimapur District, Nagaland

Dimapur (Nagaland, India) is dominated by undifferentiated hillside slopes and alluvial plains. The Muga and Eri silk industries are important cultural and economic activities for the inhabitants of Dimapur. Profitable silk production requires adequate quality and quantity of healthy leaves and is highly dependent on the soil fertility of the region. Keeping this in view, the present study was carried out as a first attempt to prepare a geographic information system (GIS) map for Muga and Eri soils in Dimapur, Nagaland. A total 65 surface (0–15 cm) soil samples from Muga farms and 79 surface soil samples from Eri farms were collected and analysed for soil pH, organic carbon content and availability of macro- and micronutrients. Soils of both Muga and Eri farms were found to be extremely (&lt;3.05) to moderately (5.09–6.84) acidic. Soils of Muga and Eri farms were found to have low to high organic carbon content (from 0.24 to 1.98%), low to high available nitrogen content (179.8–612.5 kg ha−1) and medium available phosphorus content (2.68–154.6 kg ha−1). The sulphur availability index was 0.26 and 11.81 for Muga and Eri host plant farms, respectively. The multi-macronutrient map revealed that 46.95% of the district’s total geographical area (TGA) showed deficiencies in one or more macronutrients (high priority zone). Thus, these regions need urgent attention in terms of nutrient management decisions in order to reduce the declining trend of soil fertility and achieve sustainable sericulture production.

Later, Fewer, None? Recent Trends in Cohort Fertility in South Korea

South Korea and other developed regions in East Asia have become forerunners of prolonged lowest-low fertility. South Korea's total fertility rate has been below 1.3 for two decades, the longest duration among OECD countries. Using vital statistics and census data, I study recent trends in the country's cohort fertility covering women born before the 1960s to those born in the 1980s. Analyzing outcomes at both the intensive margin of fertility (i.e., timing and number of children) and the extensive margin of family formation (i.e., marriage and childlessness), I document three novel patterns. First, the driver of low fertility has evolved across birth cohorts, from married women having later and fewer childbirths, to fewer women getting married, and finally to fewer women having children even if married. Second, a decomposition analysis of marriage and fertility changes indicates that the marriage and fertility decline was driven by changes within educational groups rather than by changes in women's educational composition. Third, the relationship between women's educational attainment and marriage or fertility was negative for the 1960s cohort, but an inverted U-shaped education gradient emerged beginning with the 1970s cohort.

Did the 1918 influenza pandemic cause a 1920 baby boom? Demographic evidence from neutral Europe

In 1919–20, the European countries that were neutral in the First World War saw a small baby bust followed by a small baby boom. The sparse literature on this topic attributes the 1919 bust to individuals postponing conceptions during the peak of the 1918–20 influenza pandemic and the 1920 boom to recuperation of those conceptions. Using data from six large neutral countries of Europe, we present novel evidence contradicting that narrative. In fact, the subnational populations and maternal birth cohorts whose fertility was initially hit hardest by the pandemic were still experiencing below-average fertility in 1920. Demographic evidence, economic evidence, and a review of post-pandemic fertility trends outside Europe suggest that the 1920 baby boom in neutral Europe was caused by the end of the First World War, not by the end of the pandemic.

From protests into pandemic: demographic change in Hong Kong, 2019–2021

ABSTRACT Compared to other settings, COVID-19 infection and death rates in Hong Kong were very low until 2022, due to top-down interventions (e.g. quarantines, ‘mask mandates’) and community activation. However, in addition to these epidemiological circumstances, Hong Kong has also undergone significant social and political change stemming from the social movement beginning in 2019 through the enacting, and aftermath, of the National Security Law. We draw on registered birth and marriage data from 2015 through 2021 to explore how fertility and nuptiality changed after the social movement followed by the first four waves of the COVID pandemic. We describe how fertility and marriage rates have changed in Hong Kong and to what extent the changes are associated with the social movement and the COVID pandemic. We further disaggregate the fertility and nuptiality trends by Hong Kong-born and non-Hong Kong-born population, with a specific focus on migrants from the Mainland.

Saudi Arabia's Maternal and Child Health Scenario Interpreted.

Countries in the Arabian Gulf, especially Saudi Arabia, deserve special attention due to the scarcity of information researched and discussed on Maternal and Child Health (MCH). This report focuses on trends in women of reproductive age, children ever born, live births, child mortality, contraception, age at marriage, and fertility rates. Data from various censuses conducted from 1992 to 2010 and demographic surveys conducted from 2000 to 2017 were used in this analysis. Over time period, the female population increased in Saudi Arabia. However, the proportion of children, ever-married women, children ever-born, and live births decreased as did child mortality. These changes in maternal and child health dimensions are owing to reforms in the health sector, including health infrastructure, in accordance with the achievements of the Sustainable Development Goals (SDGs). A comparatively higher quality of MCH was reported. However, demands and challenges of obstetric, gynecologic, and pediatric care are increasing, thus, strengthening and streamlining in accordance with fertility trends, marital patterns, and child health care is essential, for which primary data collection at regular intervals is a prerequisite.

Proximate determinants and decomposition of changes in fertility levels across Nigeria regions: Evidence from Nigeria Demographic Health Survey, 2003-2018.

There is disparity in fertility level across the six geopolitical zones in Nigeria. Deeper uunderstanding about the drivers of fertility trends are necessary to prioritize zonal specific strategies for fertility reduction in Nigeria. Thus, this study examined the proximate determinants (PDs) of fertility and decomposed the change in its level across the six geo-political zones in Nigeria. Data from Nigeria Demographic and Health Surveys of 2003 and 2018 were analyzed. Fertility data were based on the report of full birth history from women of reproductive age. The Revised Bongaarts framework was used to estimate PDs and fertility levels. The contribution of each PDs to the observed changes in fertility levels was quantified using Das Gupta's five- factor decomposition method. The Total fertility rate (TFR) in 2003 and 2008 across the zones are South-South (5.04 vs 4.36), South-West (4.88 vs 4.26), North West (7.25 vs 6.85), North East (6.87 vs 6.54), North Central (5.72 vs 5.48), South East (5.06 vs 4.86), Nigeria (6.00 vs 5.59). Across the zones, there was a change in the fertility inhibiting effect of Contraception (Cc) between 2003 and 2018. The fertility inhibiting effect of Postpartum Infecundability (Ci) and Abortion was the highest and smallest respectively across the zones. Delayed sexual exposure (Cm) and contraceptive use (Cc) contributed the most to the change across the regions. The percentage contribution of Cm in South-South, South West, and South East was 87.04%, 52.89%, and 172.85% respectively. Furthermore, most of the fertility change observed in North Central was attributable to Cc. Abortion index was not an important inhibiting factor of fertility in Nigeria. Delayed sexual exposure and contraceptive use accounted for the largest change observed in fertility levels across the six geo-political zones in Nigeria between 2003 and 2018. Strategies that promote delayed sexual exposure, contraceptive use and breast feeding practices will enhance fertility transition in Nigeria.

Declining Quantity and Quality of Births in Chile amidst the COVID‐19 Pandemic

AbstractExtensive demographic scholarship shows that the population‐level implications of mortality crises such as the COVID‐19 pandemic extend beyond mortality dynamics to affect fertility and family‐formation strategies. Using novel municipality‐level data from Chile covering all births that occurred between January 2017 and December 2021, this study explores trends in fertility and implications of the COVID‐19 pandemic for “quantum” and “quality” of births in the Chilean context. Building both a monthly and a yearly panel of 346 municipalities and leveraging fixed‐effects regression analyses, we focus on births and crude birth rates to measure quantum, while quality is assessed through the share of births that are low‐weight (LBW) and preterm (PTB). Our findings provide evidence of a significant drop in fertility in the wake of COVID—of the magnitude of a reduction of 1.3 live births per 1,000 individuals—which reaches a minimum around February 2021, followed by an incipient rebound in late 2021. Moreover, estimates on child health at birth suggest that the COVID period was associated with an increase in LBW and, foremost, PTB, by 1 and 2.2 percentage points, respectively. Findings from this study shed light on the role of policy interventions in the health arena and the linkages between short‐ and long‐run effects in relation to the various COVID‐19 waves in Chile.

Fertility trends by HIV status in a health and demographic surveillance study in Magu District, Tanzania, 1994-2018.

Sub-Saharan Africa (SSA) has the highest fertility rates and highest HIV disease burden globally. However, it is not clear how the rapid expansion of anti-retroviral therapy (ART) for HIV has impacted the fertility gap between HIV-infected and uninfected women. We used data from a Health and Demographic Surveillance System (HDSS) in north-western Tanzania to explore trends in fertility rates and the relationship between HIV and fertility over the 25-year period. From 1994 to 2018, births and population denominators from the HDSS population were used to obtain age-specific fertility rates (ASFRs) and total fertility rates (TFRs). HIV status was extracted from eight rounds of epidemiologic serological surveillances (1994-2017). Fertility rates by HIV status and in different levels of ART availability were compared over time. Independent risk factors for fertility changes were examined using Cox proportional hazard models. There were 24,662 births from 36,814 women (15-49) who contributed a total of 145,452.5 Person-Years of follow-ups. The TFR declined from 6.5 births per woman in 1994-1998 to 4.3 births per woman in 2014-2018. The number of births per woman was 40% lower in women living with HIV than in HIV-uninfected women (4.4 vs. 6.7), although this difference narrowed over time. The fertility rate in HIV-uninfected women was 36% lower in 2013-2018 than in 1994-1998(age-adjusted HR = 0.641; 95% CI 0.613-0.673). In contrast, the fertility rate in women living with HIV was relatively unchanged over the same follow up period (age-adjusted HR = 1.099; 95% CI 0.870-1.387). There was a notable fertility decline among women in the study area from 1994 to 2018. Fertility remained lower in women living with HIV than in HIV-uninfected women, but the difference continued to narrow over time. These results highlight the need for more research into fertility changes, fertility desire and family planning use in Tanzanian rural communities.

Longitudinal trends in fertility in women of advanced maternal age in the United States and Sweden from 1935–2018 and comparison to maternal mortality ratios

Advanced maternal age (AMA, >35 years at delivery) confers maternal and foetal risks, particularly with age >45 years and nulliparity, but longitudinal comparative data on age- and parity-specific AMA fertility is lacking. We used the Human Fertility Database (HFD), a publicly available, international database, to analyse fertility in US and Swedish women aged 35–54 from 1935 to 2018. Age-specific fertility rates (ASFR), total birth counts, and proportion of AMA births were evaluated across maternal age, parity, and time, and compared to maternal mortality rates during the same time. In the US, total AMA births nadired in the 1970s, and have risen since. Until 1980, most AMA births were to women completing parity 5 or higher; since then, most have been to low parity women. While ASFR in 35 to 39 year olds was highest in 2015, ASFR in women 40–44 and 45–49 were highest in 1935, though they have been rising recently, especially in low-parity women. While the same AMA fertility trends were seen in the US and Sweden from 1970–2018, maternal mortality rates have risen in the US despite remaining low in Sweden. Although AMA is known to contribute to maternal mortality, this discrepancy merits further consideration.

Projecting the Contribution of Assisted Reproductive Technology to Completed Cohort Fertility

Assisted reproductive technology (ART) is increasingly influencing the fertility trends of high-income countries characterized by a pattern of delayed childbearing. However, research on the impact of ART on completed fertility is limited and the extent to which delayed births are realized later in life through ART is not well understood. This study uses data from Australian fertility clinics and national birth registries to project the contribution of ART for cohorts of women that have not yet completed their reproductive life and estimate the role played by ART in the fertility ‘recuperation’ process. Assuming that the increasing trends in ART success rates and treatment rates continue, the projection shows that the contribution of ART-conceived births to completed fertility will increase from 2.1% among women born in 1968 to 5.7% among women born in 1986. ART is projected to substantially affect the extent to which childbearing delay will be compensated at older ages, suggesting that its availability may become an important factor in helping women to achieve their reproductive plans later in life.

The challenges of time for studies on the population effects of the COVID-19 pandemic on perinatal outcomes.

The challenges of time for studies on the population effects of the COVID-19 pandemic on perinatal outcomes.

Modern Family? The Gendered Effects of Marriage and Childbearing on Voter Turnout

AbstractIn many democracies, gender differences in voter turnout have narrowed or even reversed. Yet, it appears that women participate more in some circumstances and men in others. Here we study how life trajectories – specifically, marriage and having children – will impact male and female turnout differently, depending on household-level context. To this end, we leverage a unique administrative panel dataset from Italy, an established democracy where traditional family structures remain important. Our within-individual estimates show that marriage increases men's participation to women's higher pre-marital levels, particularly so in low-income families. We also find that infants depress maternal turnout, especially among more traditional families, whereas primary school children stimulate paternal turnout. Exploring aggregate-level consequences, we show that demographic trends in marriage and fertility have contributed to recent shifts in the gender composition of the electorate. Together, our results highlight the importance of the family as a variable in political analyses.

Growing Pains: Can Family Policies Revert the Decline of Fertility in Spain?

This article aims to analyze the capability of family policies to reverse the sharp decline in fertility that has been observed in Spain in recent decades. The analysis was carried out by applying two mathematical techniques: the genetic algorithm and the strategic scenarios. Firstly, a mathematical model was designed and validated adjusting the combined performance of fertility and family policies during the 2008–2019 period. Subsequently, this model was applied to the future (2020–2060) to extrapolate the evolution of fertility considering different models of family policies. The results demonstrate that a model of family policies that is coherent with other socially desirable objectives, such as gender and social equality, will be insufficient to reverse the current downward trend in fertility. Therefore, these outcomes point to the need to articulate and harmonize diverse public policies considering the principles of equality and well‐being to modify the recent decline in fertility. An increase in fertility must therefore be identified as a socially desirable goal and public policies must be adapted to this objective, in the understanding that fertility not only requires family policies but also their coherence with the employment and educational policies and work–life balance mechanisms offered by public institutions.

Reproductive history and breast cancer survival: Findings from the African breast cancer-Disparities in outcomes cohort and implications of Africa's fertility transition on breast cancer prognosis.

Reproductive characteristics are known risk factors for breast cancer but, other than recent birth, their role as prognostic factors is less clear, and has not been studied in Sub-Saharan Africa (SSA). In this setting, we examined whether reproductive factors independently influence breast cancer survival in a subset of the African Breast Cancer-Disparities in Outcomes cohort study. In 1485 women with incident breast cancer recruited between 2014 and 2017, we examined birth cohort changes in reproductive factors, and used Cox models to examine whether reproductive characteristics were associated with all-cause mortality after adjusting for confounders (age, stage, treatment, HIV, and social factors). Four years after diagnosis, 822 (56%) women had died. Median parity was 4 (IQR=2, 6) and 209 (28%) of premenopausal women had had a recent birth (<3 years prior to cancer diagnosis). Each pregnancy was associated with a 5% increase (95% CI: 2%, 8%) in mortality rates, which held among postmenopausal women (5%, [1%-9%]). Pre-menopausal women with a recent birth had 52% (20%, 92%) higher mortality rates. Fertility trends by birth cohort showed declining parity, increasing age at first birth and declining age at last birth, however the impact of these population-level changes on future average survival was predicted to be very small (<3% absolute gain).

Demographic Challenges in Poland Understanding Low Fertility

Research background: The phenomenon of low fertility in Poland is a vital subject of demographic analysis. In recent years, not only have there been changes in procreative and family models, but also in the age structure of society. This is particularly significant in the context of population ageing, which is becoming increasingly evident and brings numerous challenges such as increased burden on healthcare systems, a decrease in the active workforce, and the need to secure adequate retirement funds. Despite the desire to have children, many individuals refrain from making such a decision, and the reasons for this choice are diverse. Therefore, it was essential to conduct an analysis of the factors determining fertility in Poland, considering both the economic and social aspects. Understanding how the economic situation, labour market conditions, and changes in social structure impact on the decision-making process regarding childbearing is essential. Purpose of the paper: The objective of this article was to analyse fertility rates in Poland for the period 2004-2020. The conducted research identified the factors influencing the observed state of low generational replacement and determining their intensity. Methodology/Methods/Data sources: The data used in this article were sourced from the Central Statistical Office and covered the years 2004-2020. The study was based on literature concerning demography and econometrics. Three statistical methods were applied in the analysis of fertility in Poland: the Classical Method of Least Squares (CMLS) model, the Fixed Effects (FE) estimator, and the Random Effects (RE) estimator. Fertility analysis was conducted at regional level by dividing Poland into 16 administrative units (voivodeships). A panel model was employed for the analysis, and the results were subjected to Wald, Breusch-Pagan, and Hausman tests to compare the outcomes obtained from different models. Findings: The results of the analysis indicate that the economic situation and the labour market significantly influence the decision to have children in Poland. The trend of low fertility, although showing some increase, is still characteristic of the country compared to other EU nations. The analysis of the factors determining fertility is vital for understanding the decisions of young generations of Poles regarding parenthood.

Fertility and ageing – actuarial perspectives

Abstract Fertility, particularly at its current low level in many developed countries and high level in some less developed countries, is a key factor driving demographic, economic, and societal changes at local, national, and global levels. Population ageing due to low fertility and increasing longevity represents one of the most significant global megatrends and risks. Many countries are already experiencing population decline and rapid growth of their elderly populations, with implications for workforce size, economic development, health and pension schemes, and social security arrangements. Actuaries are well known for their work on mortality and morbidity, but they have rarely considered fertility and its proximate determinants, despite their demographic and economic effects. This paper explores key explanations and outcomes of past and projected future fertility trends, and the implications for actuaries and for political and economic decision-makers.

Fertility recovery despite the COVID-19 pandemic in Finland?

Finland’s increase in births, recorded in the months following the first two waves of the COVID-19 pandemic, was among the strongest. We assess whether this fertility increase occurred because of or despite the pandemic, or both, by investigating the country’s fertility trends by women’s region of residence, age group, and parity. Finland overall was modestly hit by the early pandemic, but Helsinki-Uusimaa faced more severe restrictions. We used aggregate register data until September 2021 to assess monthly fertility. In 2020 and 2021, the relative increases in fertility were strongest among women aged 30 and over. In 2021, but not in 2020, fertility increased most in Helsinki-Uusimaa, and across parities. Model-based estimates suggested a modest fertility boost of the early pandemic. To conclude, Finland’s notable fertility increase in 2021 broadly followed pre-existing trends where the country recovered from its all-time low fertility levels, and the early pandemic may have reinforced this trend.

Fertility Transition in Pakistan: Evidence from Census

In the absence of an accurate and complete registration system, efforts were made to estimate the levels of vital statistics through sample surveys. The first such effort was made through the Population Growth Estimation (PGE) project conducted from January, 1962 to December 1965. Later on, various demographic surveys were conducted almost at regular intervals and the last effort in the series was Pakistan Reproductive Health and Family Planning Survey (PRHFPS) in the year 2000-01. Although all these efforts were made to ascertain levels and trends of various demographic events, yet the estimates particularly the ones on fertility remained controversial. The first signal of fertility reduction was emanated from the 1975 Pakistan Fertility Survey (PFS) which estimated a Total Fertility Rate (TFR) of 6.3 children from over 7 children estimated earlier from PGE data. However, all hopes of the onset of fertility transition were shattered by the [Retherford’s, et al. (1987)] study entitled “Fertility Trend in Pakistan: The Decline that Wasn’t”. By using the Own Children Method, they confirmed that the decline in fertility was an artifact of the data. Another study by Shah, Pullum, and Irfan (1986) also termed the fertility decline shown by the PFS data as spurious. The Pakistan Labour Force and Migration Survey, conducted five years later, in 1979-80, estimated a TFR of 6.5 children, thus providing another proof supporting the fact that fertility had not declined to the extent believed.