Global trends in total fertility rate and its relation to national wealth, life expectancy and female education

Neonatal outcomes in infants conceived using assisted reproductive technologies: A single medical center cohort study

BACKGROUND

A significant rise in the use of assisted reproductive technology (ART) has been observed, but concerns about its impact on neonatal outcomes have been considered. The aim of this retrospective cohort study is to determine the association between ART and the risk of neonatal complications and congenital anomalies within a recent time period.

METHODS

This retrospective study enrolled infants born after 20 weeks of gestation at a tertiary hospital in Taiwan between January 2019 and December 2021. The study population was divided into two groups: (1) ART pregnancy group and (2) natural pregnancy group. Maternal and neonatal characteristics, pregnancy complications, and neonatal outcomes were compared between the two groups. Multivariate logistic regression was used to adjust for maternal characteristics, preexisting maternal conditions, pregnancy complications, delivery methods, and infant characteristics.

RESULTS

This study enrolled 1770 infants comprising 289 in the ART pregnancy group and 1481 in the natural pregnancy group. The ART pregnancy group showed higher rates of multiple births, preterm births, low birth weights, and longer hospitalization periods. In the stratified analyses that were conducted on singleton births, no significant difference was observed. In the case of multiple births, lower rates of preterm birth, low birth weight, and respiratory support were observed in the ART pregnancy group. After adjusting for maternal and infant characteristics, ART was not considered a significant risk factor for adverse neonatal outcomes, including mortality, complications, and congenital anomalies.

CONCLUSION

Although ART pregnancies were more likely to result in multiple births and furthermore adverse outcomes, ART itself was not associated with an increased risk of poor neonatal outcomes. By implementing measures to control the number of implanted embryos, ensuring appropriate prenatal screening, and providing comprehensive postnatal care, the risks associated with increased multiple pregnancies caused by ART may be reduced.

Psychometric validation of the Chinese version of the empowerment scale for pregnant women

Empowering pregnant women is a crucial process that healthcare providers should evaluate, as empowerment is a meaningful indicator that can reflect the impact of health promotion and education in antenatal care. The Empowerment Scale for Pregnant Women (ESPW) is a reliable and valid instrument for measuring empowerment. The cross-sectional study was conducted to translate and validate the psychometric properties of the ESPW among 526 pregnant women in China. The forward-backward method was used to translate the English version of the ESPW into the Chinese version. Reliability was examined with the internal consistency and test-retest coefficients. Validity was analyzed with structural, dimensionality, convergent, discriminant, and concurrent validity. The Cronbach's α value of 0.97 and the intraclass correlation coefficient of 0.98 (95% confidence interval [CI], [0.96, 0.99]) demonstrated excellent internal consistency and test-retest reliability. Exploratory factor analysis revealed that five factors with eigenvalues > 1 explained 68.41% of the total variance. Confirmatory factor analysis verified an acceptable model that fit the data exceptionally. The Chinese-translated version of the ESPW (CV-ESPW) had acceptable convergent and discriminant validity. Concurrent validity was supported by the correlation between the total scores of the CV-ESPW and the Chinese version of the Patient Perceptions of the Empowerment Scale (r = 0.64, p < 0.001). The CV-ESPW is a valid and reliable assessment tool for measuring pregnant women's empowerment in China and can potentially contribute to evaluating the effectiveness of programs that empower pregnant women.

Comparison of univariate and bivariate Poisson regression methods in the analysis of determinants of female schooling and fertility in Malawi

Recent research has established existence of a correlation between women's education and fertility, suggesting that they share similar risk factors. However, in many studies, the two variables were analysed separately, which could bias the conclusions by undermining the apparent correlations of such paired outcomes. In this article, the univariate and bivariate Poisson regression models were applied to nationally representative sample of 24,562 women from the 2015-16 Malawi demographic and health survey to examine the risk factors of women's education levels and fertility. The R software version 4.1.2 was used for the analyses. The results showed that estimates from the bivariate Poisson model were consistent with those obtained from the separate univariate Poisson models. The sizes of estimates of coefficients, their standard errors, p-values, and directions were comparable in both bivariate and univariate Poisson models. Using either the univariate or bivariate Poisson model, it was found that the age of a woman at first sexual experience, her current age, household wealth index, and contraceptive usage were significantly associated with both the woman's schooling and fertility. The study further revealed that ethnicity, religion, and region of residence impacted education level only and not fertility. Similarly, marital status and occupation impacted fertility only and not education. The study also found that higher education levels were linked to a lower number of children, with a strong negative correlation of -0.62 between the two variables. The study recommends using bivariate Poisson regression for analysing paired count response data, when there is an apparent covariance between the outcome variables. The results suggest that efforts by policymakers to achieve the desired women's sexual and reproductive health in sub-Saharan Africa should be intertwined with improving women's and girls' education attainment in the region.

Parents' age and total fertility rate in selected high-income countries from Europe and North America, 1990-2020

OBJECTIVE

To provide a comprehensive picture of trends in parents' age and total fertility rate in selected most populous high-income countries from Europe and North America.

STUDY DESIGN

Data were retrieved from official statistics published by the United Nations, the World Bank, the European Union (EU), and by national health statistics offices.

RESULTS

Mean maternal age at birth showed increasing trends in all considered countries; in 2020, the highest mean age was observed in Italy (32.2) and Spain (32.3), and the lowest one in the USA (28.8). Mean maternal age at first birth also showed upward trends. In the 1990s, mean age at first birth ranged from 25.5 to 26.9 years, except for the USA where it was below 25 years. The countries with the highest average maternal age at first birth were Italy and Spain, reaching 31 years over the most recent years. Data on mean paternal age at birth were scant. In Germany (2019) it was 34.6 and in the USA (2014) 27.9 years. In Italy, mean paternal age increased from 34.2 in 2000 to 35.5 in 2018, in the UK from 30.7 in 1990 to 33.4 in 2017, and in Canada, a decrease was observed from 29.1 in 2006 to 28.3 in 2011. Finally, Sweden and the USA had the highest fertility rates, around two children in some years, while Italy and Spain had the lowest ones, with less than 1.5 children over the whole period.

CONCLUSIONS

Monitoring of trends in reproductive factors is crucial to gain insight into society from a cultural and sociological point of view and to analyze the impact of these changes on reproductive health and related conditions.

Impact of metabolic syndrome factors on sperm DNA fragmentation in males from infertile couples: A systematic review and meta-analysis

PURPOSE

To investigate the impact of metabolic syndrome factors on sperm DNA fragmentation (sDF) in males from infertile couples.

METHODS

A systematic literature search was performed across ten databases for literature published from January 1, 2013 until September 13, 2023. The protocol has been registered on PROSPERO (CRD42023458359), and the literature search strategy is adhered to the PRISMA framework. Studies that evaluated sDF, as indicated by DNA fragmentation index (%DFI), in males from infertile couples in relation to metabolic syndrome factors were included. Meta-analysis, using random effects model and Bayesian framework network, was performed, and data were presented as Standardized Mean Differences (SMD) with corresponding 95 % Confidence Interval (CI).

RESULTS

Of the 2579 citations identified, eleven studies were included in this meta-analysis. The findings revealed that the %DFI was not associated with overall metabolic syndrome factors (p-tot = 0.235; SMD = 0.57 [95 %CI: -0.37, 1.52]), metabolic syndrome status (p-tot = 0.337; SMD = 0.08 [95 %CI: -0.08, 0.24), increased body mass index (p-tot = 0.237; SMD = 0.71 [95 %CI: -0.47, 1.89]), or glycaemic profile (p-tot = 0.93; SMD = 0.13 [95 %CI: -2.72, 2.98]). High levels of heterogeneity were observed (p < 0.01) in all subgroups, except for metabolic syndrome status.

CONCLUSION

The association between metabolic syndrome factors and sDF is conflicting. However, interpreting the association requires caution, as confounding factors, indicated by high heterogeneity, may conceal the outcome. Metabolic syndrome may influence other factors contributing to male infertility, highlighting the importance of promoting a healthy lifestyle.

Global epidemiology of epithelial ovarian cancer

Globally, ovarian cancer is the eighth most common cancer in women, accounting for an estimated 3.7% of cases and 4.7% of cancer deaths in 2020. Until the early 2000s, age-standardized incidence was highest in northern Europe and North America, but this trend has changed; incidence is now declining in these regions and increasing in parts of eastern Europe and Asia. Ovarian cancer is a very heterogeneous disease and, even among the most common type, namely epithelial ovarian cancer, five major clinically and genetically distinct histotypes exist. Most high-grade serous ovarian carcinomas are now recognized to originate in the fimbrial ends of the fallopian tube. This knowledge has led to more cancers being coded as fallopian tube in origin, which probably explains some of the apparent declines in ovarian cancer incidence, particularly in high-income countries; however, it also suggests that opportunistic salpingectomy offers an important opportunity for prevention. The five histotypes share several reproductive and hormonal risk factors, although differences also exist. In this Review, we summarize the epidemiology of this complex disease, comparing the different histotypes, and consider the potential for prevention. We also discuss how changes in the prevalence of risk and protective factors might have contributed to the observed changes in incidence and what this might mean for incidence in the future.

What is driving the global decline of human fertility? Need for a multidisciplinary approach to the underlying mechanisms

An intense period of human population expansion over the past 250 years is about to cease. Total fertility rates are falling dramatically all over the world such that highly industrialized nations, including China and the tiger economies of SE Asia, will see their populations decline significantly in the coming decades. The socioeconomic, geopolitical and environmental ramifications of this change are considerable and invite a multidisciplinary consideration of the underlying mechanisms. In the short-term, socioeconomic factors, particularly urbanization and delayed childbearing are powerful drivers of reduced fertility. In parallel, lifestyle factors such as obesity and the presence of numerous reproductive toxicants in the environment, including air-borne pollutants, nanoplastics and electromagnetic radiation, are seriously compromising reproductive health. In the longer term, it is hypothesized that the reduction in family size that accompanies the demographic transition will decrease selection pressure on high fertility genes leading to a progressive loss of human fecundity. Paradoxically, the uptake of assisted reproductive technologies at scale, may also contribute to such fecundity loss by encouraging the retention of poor fertility genotypes within the population. Since the decline in fertility rate that accompanies the demographic transition appears to be ubiquitous, the public health implications for our species are potentially devastating.

Effects of temperature anomaly on sperm quality: A multi-center study of 33,234 men

Backgrounds

Global fertility rates continue to decline and sperm quality is a prime factor affecting male fertility. Both extreme cold and heat have been demonstrated to be associated with decreased sperm quality, but no epidemiological studies have considered human adaptation to long-term temperature. Our aim was to conduct a multi-center retrospective cohort study to investigate exposure-response relationship between temperature anomaly (TA) that deviate from long-term climate patterns and sperm quality.

Methods

A total of 78,952 semen samples measured in 33,234 donors from 6 provincial human sperm banks in China were collected. This study considered heat and cold acclimatization to prolonged exposure in humans and explored the exposure-response relationship between TAs and sperm quality parameters (sperm concentrations, sperm count, progressive motility, progressive sperm count, total motility and total motile sperm count) during the hot and cold seasons, respectively. Linear mixed models and generalized linear models were built separately for specific centers to pool in a meta-analysis to obtain the pooled effect of TA on sperm quality, considering repeated measurements data structure and spatial heterogeneity.

Results

We identified an inverted U-shaped exposure-response relationship between TA and sperm quality during the hot season. Significant negative effect of anomalous cold on sperm quality during the hot season was found after additional adjustment for Body mass index, marital status and childbearing history. The heat-related TA in hot season was significantly negatively associated with sperm concentration, progressive sperm count and total motile sperm count (all P-values<0.05). After adjusting the relative humidity, the cold-related TA in cold season was negatively associated with the sperm total motility (P-values<0.05).

Conclusions

Our results suggest both heat-related and cold-related TAs are associated with decreased sperm quality. The findings highlight the importance of reducing exposure to anomalous temperatures to protect male fertility.

Impact of COVID-19 pandemic on marriage, divorce, birth, and death in Kerman province, the ninth most populous province of Iran

This study examined the impact of the COVID-19 pandemic on marriage, divorce, birth, and death rates using the Poisson regression model and an interrupted time-series Poisson regression model. Before the pandemic, marriage and birth rates were decreasing, while divorce and death rates were increasing, with only the trend in birth rates being statistically significant. The immediate effect of the pandemic was a significant decrease in the divorce rate, but there were non-significant effects on birth and marriage rates. However, in the months following the onset of the pandemic, there was a statistically significant sustained effect on increasing death and divorce rates. Forecasts based on pre-pandemic data showed that by the end of 2020, marriage, divorce, death, and birth rates were higher compared to pre-pandemic levels. In conclusion, the pandemic has greatly impacted society, particularly in terms of death and divorce rates. Birth rates were not immediately affected to the time lag between decisions and actual births. Fear of COVID-19 may have increased death rates as people avoided seeking medical help. Vaccination and effective treatment strategies are vital in reducing the pandemic's impact on mortality. Supporting families financially is important due to the role of economic issues in couples' decisions.

Number of children ever-born and its associated factors among currently married Ethiopian women: evidence from the 2019 EMDHS using negative binomial regression

BACKGROUND

Ethiopia's population is growing at about 2.7% annually with a fertility rate of 4.1 births per woman. However, as per the knowledge of the researcher, not enough studies have been done in Ethiopia to identify factors associated with women's fertility levels.

OBJECTIVE

To assess the number of children ever born and its associated factors among currently married reproductive-age Ethiopian women.

METHOD

Data of 5613 currently married women were extracted from the 2019 Ethiopian Mini Demographic and Health Survey (EMDHS). Stata version 14 was used for data extraction, processing, and analysis. Descriptive data were summarized using descriptive statistics. A multivariable negative binomial regression was used for the inferential analysis. Incidence rate ratio (IRR) and its 95% CI were respectively used to measure the associations and their statistical significance.

RESULT

The median number of children ever born per currently married Ethiopian woman was 3 with an iterquarter range of 4 (1-5) children. Age of a woman at her first birth (aIRR = 0.958, 95% CI: 0.954, 0.961), being protestant (aIRR = 1.128, 95%CI: 1.068, 1.193), being Muslim (aIRR = 1.096, 95% CI: 1.043, 1.151), and being from other religious groups than Orthodox Christianity (aIRR = 1.353, 95% CI: 1.036, 1.766) are positively associated with bearing more children. On the other hands, completing primary education (aIRR = 0.664, 95% CI: 0.640,0.689), secondary education(aIRR = 0.541, 95%CI: 0.504,0.582), higher education(aIRR = 0.527, 95%CI: 0.479, 0.580), being from a richest household(aIRR = 0.899, 95%CI: 0.840, 0.962), using modern contraceptive (aIRR = 0.877, 95%CI: 0.847, 0.908), living in the Afar (aIRR = 0.785, 95%CI: 0.718,0.859), Amhara (aIRR = 0.890, 95%CI: 0.718,0.859), Gambella (aIRR = 0.894, 95%CI: 0.820,0.974), and Addid Ababa(0.845, 95%CI: 0.760,0.939) are negatively associated with bearing more children.

CONCLUSION

Promoting women's empowerment, encouraging women's academic advancement, and community-based educational intervention are recommended to have optimal and decreased numbers of children.

A bivariate Poisson regression to analyse impact of outlier women on correlation between female schooling and fertility in Malawi

BACKGROUND

Women's levels of education and fertility are commonly associated. In Sub-Saharan Africa, the pace of decreasing fertility rates varies greatly, and this is linked to women's levels of education. However, this association may be influenced by unusual females who have uncommon measurements on both variables. Despite this, most studies that researched this association have only analysed the data descriptively, without taking into account the effect of potential outliers. This study aimed to examine the presence and impact of outlier women on the relationship between female education and fertility in Malawi, using regression methods.

METHODS

To analyse the correlation between women's schooling and fertility and evaluate the effect of outliers on this relationship, a bivariate Poisson model was applied to three recent demographic and health surveys in Malawi. The R software version 4.3.0 was used for model fitting, outlier computations, and correlation analysis. The STATA version 12.0 was used for data cleaning.

RESULTS

The findings revealed a correlation of -0.68 to -0.61 between schooling and fertility over 15 years in Malawi. A few outlier women were identified, most of whom had either attended 0 or at least 9 years of schooling and had born either 0 or at least 5 children. The majority of the outliers were non-users of modern contraceptive methods and worked as domestic workers or were unemployed. Removing the outliers from the analysis led to marked changes in the fixed effects sizes and slight shifts in correlation, but not in the direction and significance of the estimates. The woman's marital status, occupation, household wealth, age at first sex, and usage of modern contraceptives exhibited significant effects on education and fertility outcomes.

CONCLUSION

There is a high negative correlation between female schooling and fertility in Malawi. Some outlier women were identified, they had either attended zero or at least nine years of schooling and had either born zero or at least five children. Most of them were non-users of modern contraceptives and domestic workers. Their impact on regression estimates was substantial, but minimal on correlation. Their identification highlights the need for policymakers to reconsider implementation strategies for modern contraceptive methods to make them more effective.

The causal effect of educational attainment on stress urinary incontinence: a two-sample mendelian randomization study

BACKGROUND

Stress urinary incontinence (SUI) is characterized by involuntary urine leakage in response to increased abdominal pressure, such as coughing, laughing, or sneezing. It significantly affects women's quality of life and imposes a substantial disease burden. While pregnancy and childbirth have been previously identified as risk factors for SUI, educational attainment may also play a role. Therefore, this paper investigates the causal relationship between educational attainment and SUI using two-sample Mendelian randomization (TSMR) analysis, years of schooling (YOS), and college or university degree (CUD) as proxies.

METHODS

Summary statistics of YOS, CUD, and SUI were obtained from genome-wide association studies (GWAS), and TSMR analysis was applied to explore potential causal relationships between them. Causal effects were mainly estimated using the standard inverse variance weighting (IVW) method, and complementary and sensitivity analyses were also performed using multiple methods.

RESULTS

The results indicate that both YOS (OR = 0.994, 95% CI: 0.992-0.996; P = 7.764E-10) and CUD (OR = 0.987, 95% CI: 0.983-0.991; P = 1.217E-09) may have a negative causal effect on SUI.

CONCLUSIONS

Improving educational attainment may go some way towards reducing the risk of SUI. Therefore, it is important to increase efforts to improve the imbalance in educational development and safeguard women's health.

Global burden and trends of ectopic pregnancy: An observational trend study from 1990 to 2019

BACKGROUND

Ectopic pregnancy (EP) is one of the leading causes of death in women in early pregnancy, and the mortality of EP have gradually decreased over time in developed countries such as the United Kingdom and the United States. However, epidemiological information on EP has been lacking in recent years, so we analyzed EP data over a thirty-year period from 1990-2019 with the help of Global Burden of Disease study (GBD) data to fill this gap.

METHODS

According to the EP data in GBD for the three decades from 1990 to 2019, we used estimated annual percentage changes (EAPC) to assess the trend of age-standardized incidence rate (ASIR), age-standardized death rate (ASDR) and age-standardized disability adjusted life years (AS-DALYs) trends in EP and to explore the correlation between socio-demographic index (SDI) stratification, age stratification and EP.

RESULTS

Global ASIR, ASDR, AS-DALYs for EP in 2019 are 170.33/100,000 persons (95% UI: 133.18 to 218.49), 0.16/100,000 persons (95% UI, 0.14 to 0.19) and 9.69/100,000 persons (95% UI, 8.27 to 11.31), respectively. At the overall level, ASDR is significantly negatively correlated with SDI values (R = -0.699, p < 0.001). Besides that, ASDR and AS-DALYs have basically the same pattern. In addition, iron deficiency is one of the risk factors for EP.

CONCLUSIONS

In the past three decades, the morbidity, mortality and disease burden of EP have gradually decreased. It is noteworthy that some economically disadvantaged areas are still experiencing an increase in all indicators, therefore, it is more important to strengthen the protection of women from ethnic minorities and low-income groups.

Reproduction in a changing world

Although the global population continues to increase, the total fertility rate in many high-income countries (HICs) is below replacement, a trend apparent over several decades. The timing and pace of this change will shape the age distribution in these countries, leading to an increasing proportion of older people. The well-established links of the "demographic transition" between improving female education and improved access to contraception continue to drive down the fertility rates in low-/middle-income countries. However, changes in the age distribution will not be as marked as in HICs in the coming decades. These relationships may now be changing in some HICs with greater prosperity at both the personal (in some sectors of society) and national levels, linked to an increase in the total fertility rates despite continuing trends toward older age at first birth. Key drivers in these countries include improved provision of free/low-cost childcare, paid parental leave, and higher paternal contributions to childcare. However, there is also an increase in the number of women who do not have children or who may be unable to complete their family plans. Coronavirus disease 2019 and environmental factors, including the increasing prevalence of obesity, add to pressures on the fertility rates. Variable knowledge of the realities of female reproductive aging, particularly by men, is also a contributing factor, and this complex mix has fueled the increase in the number of elective egg freezing.

Urban population prediction based on multi-objective lioness optimization algorithm and system dynamics model

Population size is closely related to economic and social development and change. It is one of the primary and essential elements of overall urban development planning to formulate a population development strategy scientifically through population projections. Therefore, we propose an urban population prediction model based on a multi-objective lioness optimization algorithm and system dynamics. The multi-objective lioness optimization algorithm is used to optimize some critical parameters of the system dynamics model to reduce the subjectivity of the model construction. Taking Xi'an as an example, the validity of the model is verified, and the population size of Xi'an from 2019 to 2050 is predicted by the model. In addition, the impact of different policies and their combinations on the future population is discussed through simulations of three scenarios composed of five policy factors: birth, employment, science and technology, healthcare and education. The results show that the total population of Xi'an will peak at 147,939,242 in 2040, based on current development trends. Moreover, the five policies with the largest to smallest positive effect on population size are: employment policy, fertility policy, education policy, science and technology policy, and health policy, with employment and fertility policies having significantly larger effects than the other three. Therefore, the employment policy and the birth policy are the two most effective policies to promote population growth, and the coordinated implementation of the five policies is the fastest way to increase population size.

The Importance of Natural Antioxidants in Female Reproduction

Oxidative stress (OS) has an important role in female reproduction, whether it is ovulation, endometrium decidualization, menstruation, oocyte fertilization, or development andimplantation of an embryo in the uterus. The menstrual cycle is regulated by the physiological concentration of reactive forms of oxygen and nitrogen as redox signal molecules, which trigger and regulate the length of individual phases of the menstrual cycle. It has been suggested that the decline in female fertility is modulated by pathological OS. The pathological excess of OS compared to antioxidants triggers many disorders of female reproduction which could lead to gynecological diseases and to infertility. Therefore, antioxidants are crucial for proper female reproductive function. They play a part in the metabolism of oocytes; in endometrium maturation via the activation of antioxidant signaling pathways Nrf2 and NF-κB; and in the hormonal regulation of vascular action. Antioxidants can directly scavenge radicals and act as a cofactor of highly valuable enzymes of cell differentiation and development, or enhance the activity of antioxidant enzymes. Compensation for low levels of antioxidants through their supplementation can improve fertility. This review considers the role of selected vitamins, flavonoids, peptides, and trace elements with antioxidant effects in female reproduction mechanisms.

Paraben exposure and couple fecundity: a preconception cohort study

STUDY QUESTION

Is pre-conception exposure to parabens associated with fecundity in couples of childbearing age?

SUMMARY ANSWER

Paraben exposure in female partners was associated with reduced couple fecundity and anti-Müllerian hormone (AMH) might be one of the possible mediators.

WHAT IS KNOWN ALREADY

The reproductive toxicity of parabens, a class of widely used preservatives, has been suggested but evidence regarding their effects on couple fecundity is scarce.

STUDY DESIGN, SIZE, DURATION

In this couple-based prospective cohort study, a total of 884 pre-conception couples who participated in the Shanghai Birth Cohort between 2013 and 2015 were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Concentrations of six parabens were measured in urine samples collected from couples. Malondialdehyde, C-reactive protein, and AMH were assessed in female partners. The outcomes included couple fecundability (time-to-pregnancy, TTP) and infertility (TTP > 12 menstrual cycles). Partner-specific and couple-based models were applied to estimate the associations. The joint effect of paraben mixture on couple fecundity was estimated by quantile-based g-computation (q-gcomp). Mediation analysis was used to assess the mediating roles of oxidative stress, inflammation and ovarian reserve.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 525 couples (59.4%) conceived spontaneously. In the partner-specific model, propyl paraben (PrP), butyl paraben (BuP), and heptyl paraben (HeP) in female partners were associated with reduced fecundability (fecundability odds ratio (95% CI): 0.96 (0.94-0.98) for PrP; 0.90 (0.87-0.94) for BuP; 0.42 (0.28-0.65) for HeP) and increased risk of infertility (rate ratio (95% CI): 1.06 (1.03-1.10) for PrP; 1.14 (1.08-1.21) for BuP; 1.89 (1.26-2.83) for HeP). Similar associations were observed in the couple-based model. AMH played a significant mediation role in the association (average causal mediation effect (95% CI): 0.001 (0.0001-0.003)). Paraben exposure in male partners was not associated with couple fecundity. The joint effect of paraben mixture on couple fecundity was non-significant.

LIMITATIONS, REASONS FOR CAUTION

Self-reported pregnancy and single urine sample may lead to misclassification. The mediation analysis is limited in that levels of sex hormones were not measured. The inclusion of women with irregular menstrual cycles might affect the results. It is possible that the observed association was due to reverse causation.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study to assess the effects of paraben exposure on couple fecundity in Asians. Given the widespread exposure to parabens in couples of childbearing age, the present findings may have important public health implications.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported in part by the National Natural Science Foundation of China (41991314), the Shanghai Science and Technology Development Foundation (22YF1426700), the Science and Technology Commission of Shanghai Municipality (21410713500), and the Shanghai Municipal Health Commission (2020CXJQ01). All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Fertility Intention to Have a Third Child in China following the Three-Child Policy: A Cross-Sectional Study

China's three-child policy was implemented in May 2021 to stimulate a rise in fertility levels. However, few previous studies have explored fertility intentions to have a third child and have only focused on childless or one-child populations, resulting in a gap in findings between fertility intention and fertility behavior. Thus, we conducted a nationwide cross-sectional study on 1308 participants with two children. Results showed that only 9.6% of participants reported planning to have a third child and 80.2% of the population had heard of the policy but had no idea of the detailed contents. Participants with two daughters (OR = 3.722, 95% CI = 2.304-6.013) were willing to have one more child. Instrumental values (OR = 1.184, 95% CI = 1.108-1.265) and policy support (OR = 1.190, 95% CI = 1.124-1.259) were the facilitators. Perceived risk (OR = 0.883, 95% CI = 0.839-0.930) and higher educational level (OR = 0.693, 95% CI = 0.533-0.900) were the leading barriers to having one more child. Therefore, the government should deepen parents' understanding of the "three-child policy" and devise ways of reducing the negative impacts of having a third child to boost the intention to have more children. Our proposed approach can also be used to better understand the reasons for low fertility rates in other countries.