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India reached the replacement level of fertility in 2020. However, the journey of fertility transition is unconventional and heterogeneous within the country and across the different socio-economic groups. The fertility transition is considered to be faster than its socio-economic and health transition in several states. Thus, it has been presumed that the returns to fertility decline are heterogeneous across the states and population sub-groups. Our specific hypothesis is that although rich and poor, and educated and un-educated, everyone had significantly contributed to the fertility decline in response to family planning policies, only those socio-economically better-off have been investing relatively more in their children compared to the poor, and this has led to diverging destinies for children. We tested this supposition using a macro-level panel dataset (1992-2021), fixed and random effects, and IV regression models. The results confirm that child health care and outcomes have diverged while fertility declined from 1992 to 2021. These results are sustained in multiple robustness checks. While fertility is declining with highly state-sponsored family planning programmes, the persistent socio-economic inequalities are leading to unequal progress in health outcomes for children in India.

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Introduction: few studies have examined the factors influencing fertility differentials and the variation in their effects in countries with different socioeconomic and cultural backgrounds and different fertility transition paces. To address this gap, our study sought to first identify the factors that influenced fertility differentials in Morocco and Burundi during their fertility transition periods, and then to compare the effects of these factors between the two countries. Methods: using data from the 2003-4 Morocco and 2010 Burundi Demographic and Health Surveys, bivariable and multivariable Poisson regression analyses offset by the natural logarithm of the women´s age were performed to identify the socioeconomic and cultural factors that influenced fertility differentials in Morocco and Burundi during their fertility transition. Results: our main findings showed that the total number of children ever born ranged from 0 to 17 with a mean of 2.71 ± 2.89 in Burundi and from 0 to 16 with a mean of 1.88 ± 2.80 in Morocco. In Burundi, both socioeconomic and cultural factors like rural residence adjusted incident rate ratio (AIRR) = 1.159, 95% CI: 1.103 - 1.217, P=0.020), women´s illiteracy (AIRR=1.465, 95% CI: 1.241- 1.729, P <0.001) and agricultural profession (AIRR=1. 332, 95% CI: 1.263 - 1.401, P = 0.004), household poverty (AIRR= 1.381, 95% CI: 1.223 - 1.431, p<0.001), infant mortality (AIRR= 1.602, 95% CI: 1.562 - 1.643, p<0.001), early marriage (AIRR= 1.313, 95% CI: 1.264 - 1.364, p<0.001), lack of knowledge of any contraceptives (AIRR= 1.263, 95% CI: 1.125 - 1.310, p = 0.003) and failure to use modern contraceptives (AIRR= 1.520, 95% CI: 1.487 - 1.611, p<0.001) were associated with high number of children ever born. However, in Morocco socioeconomic factors like residence place, women´s agricultural profession and household poverty were not significant. In this country, women´s illiteracy (AIRR=1.428, 95% CI: 1.315 - 1.551, P <0.001), lack of access to mass media (AIRR= 1.241, 95% CI: 1.108 - 1.375, p = 0.006), infant mortality (AIRR=1.222, 95%CI: 1.184 - 1.361, p<0.001), early marriage (AIRR1.481, 95% CI: 1.435 - 1.529, p<0.001), lack of knowledge of any contraceptives (AIRR1.508, 95% CI: 1.409 - 1.613, p<0.001) and failure to use modern contraceptives (AIRR1.745, 95% CI: 1.627 - 1.863, p<0.001) were associated with high fertility but with different effects than in Burundi. Conclusion: the evidence from this study suggests that interventions to accelerate the fertility transition processes in Burundi and many other countries with slow fertility transitions should be designed and implemented according to each country's local context.

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The DRC has one of the highest fertility rates globally, yet research on fertility preferences in the country remains limited. This study aims to identify the factors contributing to the persistence of high fertility preferences among young and adolescent women (15-24) in the DRC. Using data from the 2013-2014 DHS, the study examines fertility preferences by transition stage. Multinomial logistic regression analysis is used to identify the characteristics associated with mid- (4-5 children) and pre-transitional (6+ children) as opposed to post-transitional (0-3 children) preferences. Results reveal that 43% of the women prefer 6+ children. The relative risk of fertility preference varies significantly based on characteristics such as age, literacy, place and province of residence, religion, employment status, wealth, acceptance of domestic violence, and knowledge of modern family planning methods. The findings provide evidence for both the diffusion and socio-economic theory of fertility decline.

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The lagging fertility transition in West Africa has important repercussions for global population growth but remains poorly understood. Inspired by Caldwell and colleagues' fertility transition framework, as well as by subsequent research, we examine diversity in women's holistic childbearing trajectories in Niakhar, Senegal, between the early 1960s and 2018 using a sequence analysis approach. We evaluate the prevalence of different trajectories, their contribution to overall fertility levels, and their association with women's socioeconomic and cultural characteristics. Four trajectories were observed: "high fertility," "delayed entry," "truncated," and "short." While the high fertility trajectory was most prevalent across cohorts, delayed entry grew in importance. The high fertility trajectory was more common among women born between 1960 and 1969 and was followed less often by divorced women and those from polygynous households. Women with primary education and those from higher status groups were more likely to experience delayed entry. The truncated trajectory was associated with lack of economic wealth, polygynous households, and caste membership. A short trajectory was related to lack of agropastoral wealth, divorce, and possibly secondary sterility. Our study advances knowledge on fertility transitions in Niakhar-and Sahelian West African contexts more generally-by showing the diversity of childbearing trajectories within high fertility regional contexts.

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Can the names parents gave their children give us insights into how parents in historical times planned their families? In this study, we explore whether the names given to the firstborn child can be used as indicators of family-size preferences and, if so, what this reveals about the emergence of intentional family planning over the course of the demographic transition. We analyze historical populations from 1850 to 1940 in the United States, where early fertility control and large sample sizes allow separate analyses of the White and Black populations. We also analyze Norway from 1800 to 1910, where there was a much later fertility transition. A split-sample method allows automated scoring of each name in terms of predicted family size. We find a strong relationship between naming and family size in the U.S. White population as early as 1850, for the Black population beginning in 1940, and for the Norwegian population in 1910. These results provide new evidence of the emergence of "conscious calculation" during the fertility transition. Our methods may also be applicable to modern high-fertility populations in the midst of fertility decline.

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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).

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Thermosensitive genic male sterility (TGMS) has been widely used in two-line hybrid rice breeding. Due to hybrid seed production being highly affected by changeable environments, its application scope is limited to some extent. Thus, it is of great importance to identify potential TGMS genes in specific rice varieties. Here, Diannong S-1 xuan (DNS-1X), a reverse TGMS (RTGMS) japonica male sterile line, was identified from Diannong S-1. Genetic analysis showed that male sterility was tightly controlled by a single recessive gene, which was supported by the phenotype of the F1 and F2:3 populations derived from the cross between DNS-1X and Yunjing 26 (YJ26). Combining simple sequence repeat (SSR) markers and bulked segregation analysis (BSA), we identified a 215 kb region on chromosome 10 as a candidate reverse TGMS region, which was designated as rtms1-D. It was narrower than the previously reported RTGMS genes rtms1 and tms6(t). The fertility conversion detected in the natural environment showed that DNS-1X was sterile below 28-30 °C; otherwise, it was fertile. Histological analysis further indicated that the pollen abortion was occurred in the young microspore stage. This study will provide new resources for two-line hybrid rice and pave the way for molecular breeding of RTGMS lines.

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The last four decades have witnessed large declines in fertility globally. This study uses data from 78 low- and middle-income countries to examine concurrent trends in unwanted fertility. Three measures of unwanted fertility are contrasted: the conventional unwanted total fertility rate, a proposed conditional unwanted fertility rate, and the percentage of births unwanted. Incidence of unwanted births and prevalence of exposure to unwanted births are both derived from answers to questions on prospective fertility preference, recognized as the most valid and reliable survey measure of preferences. Country-level trends are modeled both historically and with the decline in total fertility, with a focus on regional differentials. Results show that unwanted fertility rates-especially the conditional unwanted fertility rate-have declined substantially in recent decades. By contrast, the percentage of births unwanted has declined less, remaining stable or even increasing: from a birth cohort perspective, declines in unwanted fertility have been far more modest than the increased parental success in avoiding unwanted births. The regional patterns suggest that sub-Saharan Africa has several similarities with other major regions but also some peculiar features, including a recent stall in the decline of unwanted fertility that persists after controlling for the stage of fertility transition.

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The interplay between remarriage and fertility is among the most poorly documented subjects in sub-Saharan Africa (SSA), despite remarriage being one of the fundamental aspects of marriage dynamics in this region. We use Demographic and Health Survey data from 34 countries in SSA to document the association between remarriage and fertility during the reproductive years and over the fertility transition. The findings show that in 29 countries, remarried women end up having fewer children than women in intact unions, despite attaining similar or higher levels of fertility at early reproductive ages. However, remarriage is found to have a positive effect on fertility in Sierra Leone. The effects of remarriage on fertility diminish as fertility declines, with smaller effects generally observed in countries that are relatively advanced in their fertility transition and larger effects found elsewhere. These findings shed light on the role that remarriage might play in country-level fertility declines.

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India is currently one of the most demographically diverse regions of the world. Fertility and mortality rates are known to show considerable variation at the level of regions, states and districts. Little is known however, about the spatial variations of the contraceptive usage-a critical variable that is relevant to fertility as well as health policy. This paper uses data from four national population-based household surveys conducted between 1998 and 2016 to explore district-level variations in the contraceptive prevalence rate. We find no clear evidence of convergence. The gap between the best and worst performing districts is more than 70 percent across the four rounds and does not diminish over time. We also find considerable evidence of spatial clustering across districts. Districts with high prevalence concentrate in Southern states and more recently, in the Northeast of the country. Our analysis suggests that female literacy and health care infrastructure are important correlates of spatial clusters. This suggests that investments in women's human capital and health-care infrastructure play a role in expanding women's opportunities to time their births.

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Based on an analysis of the life trajectories of 2510 conscripts and their families from a Spanish rural area in the period 1835-1977, this paper studies the development of the fertility transition in relation to height using bivariate analyses. The use of heights is an innovative perspective of delving into the fertility transition and social transformation entailed. The results confirm that the men with a low level of biological well-being (related to low socio-economic groups) were those who started to control their fertility, perhaps due to the effect that increased average family size had on their budget. The children of individuals who controlled their fertility were taller than the children of other families. Therefore, the children of parents who controlled their fertility experienced the largest intergenerational increase in height (approximately 50% higher). This increase could be due to the consequence of a greater investment in children (Becker's hypothesis) or a greater availability of resources for the whole family (resource dilution hypothesis).

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BACKGROUND: Photo-thermo-sensitive genic male sterile (PTGMS) rice (Oryza sativa L.) is usually considered two-line male sterile rice because of its dual-purpose in two-line hybrid rice system: under short days and low temperatures, it is fertile and used for self-propagation, but under long days and high temperatures, it is sterile and used for hybrid seed production. Therefore, photoperiod and temperature conditions are extremely important for the fertility transition of two-line male sterile rice. In recent years, there have been frequent occurrences of abnormally low-temperature (ALT) resulting in failure of two-line hybrid rice seed production. The daily average temperature (DAT) during ALT events is sometimes higher than the critical sterility-inducing temperature (CSIT) of two-line male sterile rice, of which the night temperature is lower than the CSIT. DAT has been traditionally used as the single indicator of pollen fertility transition, but it is unknown why the fertility of two-line male sterile rice in seed production restored fertility under ALT conditions. RESULTS: For Hang93S (H93S), a newly released PTGMS line, we hypothesized fertility transition is determined mainly by the cumulative effective low temperature (ELT) and only a certain duration of low temperature is required every day during the fertility-sensitive period. This study simulated ALTs where the DAT was higher than the CSIT while some segments of night temperature were lower than the CSIT. The results showed H93S exhibited a fertility transition to varying degrees. Moreover, fertility was restored under simulated ALT conditions and pollen fertility increased with increasing cumulative ELT, indicating that the fertility transition was affected primarily by the cumulative ELT. Results also indicated that pollen fertility increased as the number of treatment days increased. CONCLUSIONS: The fertility transition is caused mainly by the cumulative ELT. In two-line male sterile rice breeding, the effects of day length, ALT at night, and continuous response days should be considered together. The present study provides new insight into fertility transition so breeders can more effectively utilize the two-line male sterile rice, H93S, in breeding programs.

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We use individual-level census data for England and Wales for the period 1851-1911 to investigate the interplay between social class and geographical context determining patterns of childbearing during the fertility transition. We also consider the effect of spatial mobility or lifetime migration on individual fertility behavior in the early phases of demographic modernization. Prior research on the fertility transition in England and Wales has demonstrated substantial variation in fertility levels and declines by different social groups; however, these findings were generally reported at a broad geographical level, disguising local variation and complicated by residential segregation along social class and occupational lines. Our findings confirm a clear pattern of widening social class differences in recent net fertility, providing strong support for the argument that belonging to a certain social group was an important determinant of early adoption of new reproductive behavior in marriage in England and Wales. However, a relatively constant effect of lower net fertility among long-distance migrants both before the transition and in the early phases of declining fertility indicates that life course migration patterns were most likely factor in explaining the differences in fertility operating through postponement of marriage and childbearing.

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This study applies survival analysis to the birth histories from 317 national surveys to model pathways to low fertility in 83 less-developed countries between 1965 and 2014. It presents period measures of parity progression, the length of birth intervals and total fertility that have been standardized fully for age, parity, and interval duration. It also examines parity-specific trends in the proportion of women who want no more children. Outside sub-Saharan Africa, fertility transition was dominated by parity-specific family size limitation. As the transition progressed, women also began to postpone their next birth for lengthy periods in many countries. During the first half of the fertility transition in much of sub-Saharan Africa and in some other countries, however, women stopped childbearing without targeting particular family sizes. Moreover, birth intervals in sub-Saharan Africa have been lengthening since the onset of the transition. Birth control is not restricted to a dichotomy between limitation and spacing. Other reasons for curtailing childbearing and postponing having another birth also shape countries' pathways through fertility transition.

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Long non-coding RNAs (lncRNAs) act as universal regulators of various biological processes, but no genome-wide screening of lncRNAs involved in the fertility transition of the photo-thermosensitive genic male sterile (PTGMS) rice line has been reported. Here, we performed strand-specific RNA sequencing at three developmental stages of a novel PTGMS line Wuxiang S (WXS). A total of 3,948 lncRNAs were identified; 622 of these were detected as differentially expressed lncRNAs (DE-lncRNAs) between male-sterile WXS (WXS-S) and male-fertile WXS (WXS-F). A large proportion of lncRNAs differentially expressed at the stage of pollen mother cells meiosis, suggested that it may be the most critical stage for fertility transition of WXS. Furthermore, functional annotation of the cis- and trans- targets of DE-lncRNAs showed that 150 targets corresponding to 141 DE-lncRNAs were identified as involved in anther and pollen development. Moreover, computational analysis predicted 97 lncRNAs as precursors for 72 miRNAs, and 94 DE-lncRNAs as potential endogenous target mimics (eTMs) for 150 miRNAs. Finally, using the dual luciferase reporter assays, we demonstrated that two lncRNAs act as eTMs to regulate the expression of the SPL and GRF genes by competing for the shared osa-miR156 and osa-miR396, respectively. These genomic characteristics, differential expression, and interaction of lncRNAs with miRNAs and mRNAs contribute to our understanding of the roles of lncRNAs during the fertility transition in PTGMS rice lines.

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Studies have shown mixed associations between wealth and fertility, a finding that has posed ongoing puzzles for evolutionary theories of human reproduction. However, measures of wealth do not simply capture economic capacity, which is expected to increase fertility. They can also serve as a proxy for market opportunities available to a household, which may reduce fertility. The multifaceted meaning of many wealth measures obscures our ability to draw inferences about the relationship between wealth and fertility. Here, we disentangle economic capacity and market opportunities using wealth measures that do not carry the same market-oriented biases as commonly used asset-based measures. Using measures of agricultural and market-based wealth for 562,324 women across 111,724 sampling clusters from 151 DHS surveys in 64 countries, we employ a latent variable structural equation model to estimate (a) latent variables capturing economic capacity and market opportunity and (b) their effects on completed fertility. Market opportunities had a consistent negative effect on fertility, while economic capacity had a weaker but generally positive effect on fertility. The results show that the confusion between operational measures of wealth and the concepts of economic capacity can impede our understanding of how material resources and market contexts shape reproduction.

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BACKGROUND: Circular RNAs (circRNAs) are known to play an important role in the regulation of gene expression in eukaryotes. Photo-thermosensitive genic male sterile (PTGMS) is a very important germplasm resource in two-line hybrid rice breeding. Although many circRNAs have been identified in rice (Oryza sativa L.), little is known about the biological roles of circRNAs in the fertility transition of the PTGMS rice line. RESULTS: In the present study, RNA-sequencing libraries were constructed from the young panicles of the Wuxiang S sterile line rice (WXS (S)) and its fertile line rice (WXS (F)) at three development stages with three biological replicates. A total of 9994 circRNAs were obtained in WXS rice based on high-throughput strand-specific RNA sequencing and bioinformatic approaches, of which 5305 were known circRNAs and 4689 were novel in rice. And 14 of 16 randomly selected circRNAs were experimentally validated with divergent primers. Our results showed that 186 circRNAs were significantly differentially expressed in WXS (F) compared with WXS (S), of which 97, 87 and 60 circRNAs were differentially expressed at the pollen mother cell (PMC) formation stage (P2), the meiosis stage (P3) and the microspore formation stage (P4), respectively. Fertility specific expression patterns of eight circRNAs were analysis by qRT-PCR. Gene ontology (GO) and KEGG pathway analysis of the parental genes of differentially expressed circRNAs (DECs) revealed that they mainly participated in various biological processes such as development, response to stimulation, hormonal regulation, and reproduction. Furthermore, 15 DECs were found to act as putative miRNA sponges to involved in fertility transition in PTGMS rice line. CONCLUSION: In the present study, the abundance and characteristics of circRNAs were investigated in the PTGMS rice line using bioinformatic approaches. Moreover, the expression patterns of circRNAs were different between WXS (F) and WXS (S). Our findings primarily revealed that circRNAs might be endogenous noncoding regulators of flower and pollen development, and were involved in the fertility transition in the PTGMS rice line, and guide the production and application of two-line hybrid rice.

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Most studies on the fertility transition have focused either on macro-level trends or on micro-level patterns with limited geographic scope. Much less attention has been given to the interplay between individual characteristics and contextual conditions, including geographic location. Here we investigate the relevance of geography and socioeconomic status for understanding fertility variation in the initial phase of the Swedish fertility transition. We conduct spatially sensitive multilevel analyses on full-count individual-level census data. Our results show that the elite constituted the vanguard group in the fertility decline and that the shift in fertility behavior occurred quickly among them in virtually all parts of Sweden. Other socioeconomic status groups experienced the decline with some delay, and their decline patterns were more clustered around early centers of the decline. Long-distance migrants initially had higher fertility than people living close to their birthplace. However, as the fertility decline unfolded, this advantage was either reduced or reversed. This supports the view that migration and fertility are linked in this process. Our results confirm that socioeconomic status differences were of considerable relevance in structuring the fertility transition. The degree to which spatial distance fostered spatial variation in the fertility decline seems to have been negatively correlated with socioeconomic status, with the pattern of decline among the elite showing the lowest degree of spatial variation.

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A growing body of research has argued that the traditional categories of stopping and spacing are insufficient to understand why individuals want to control fertility. In a series of articles, Timæus, Moultrie, and colleagues defined a third type of fertility motivation-postponement-that reflects a desire to avoid childbearing in the short term without clear goals for long-term fertility. Although postponement is fundamentally a description of fertility desires, existing quantitative research has primarily studied fertility behavior in an effort to find evidence for the model. In this study, we use longitudinal survey data to consider whether postponement can be identified in standard measures of fertility desires among reproductive-age women in rural Mozambique. Findings show strong evidence for a postponement mindset in this population, but postponement coexists with stopping and spacing goals. We reflect on the difference between birth spacing and postponement and consider whether and how postponement is a distinctive sub-Saharan phenomenon.

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Existing knowledge of Tibetan historical population development is mostly based on 'best-guess' estimates and is heavily politicized. Using census data, I reconstruct the development of Tibetan fertility in China since the 1940s, with the objective of providing an independent assessment that can be used as benchmark for future studies and debates on Tibetan demography. Following major social and economic transformations starting in the 1950s, Tibetan fertility unexpectedly increased from the late 1950s to the late 1960s. As noted in several existing studies, Tibetan fertility in China then declined swiftly from the early 1980s onwards and has now reached values close to replacement level. Focusing on the 1950-70 period, I examine factors that contributed to shaping the Tibetan fertility increase in more detail. This confirms that changes in nuptiality and disease-related infertility both played a role in pushing up fertility rates among Tibetan women in China.

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