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PurposeSustainable Aviation Fuel (SAF) is crucial for aviation decarbonization, but its current pre-blending process at refineries presents challenges, including fixed blending ratios, higher transportation costs and long lead times. This study explores the potential of an innovative technology that enables on-site SAF blending at airports. By postponing blending to the point of use, this approach offers customization opportunities. However, the precise benefits and trade-offs of this concept remain unclear. The research aims to assess the impact of on-site blending on fuel price, lead time, carbon emissions and supply chain costs.Design/methodology/approachThis empirical study evaluates the effects of SAF postponement using case analyses of Singapore-Seletar and Maastricht airports. The analysis incorporates cost modeling, lead time assessment and carbon impact calculations to quantify the implications of shifting blending downstream to airport sites. Data sources include industry reports, airport-specific logistics information and SAF supply chain parameters. A comparative analysis is conducted to determine optimal airport conditions for SAF postponement, highlighting key enablers and barriers to implementation.FindingsThe results indicate that on-site SAF blending can create competitive advantages by reducing supply chain costs and lowering carbon emissions. The benefits are contingent on airport-specific factors, such as Hydroprocessed Esters and Fatty Acids availability, logistics infrastructure and regulatory conditions. The findings suggest that certain airports, particularly those with strategic locations and favorable cost structures, are better suited for adopting SAF postponement. By shifting production downstream, airports can achieve greater flexibility in SAF blending ratios while minimizing logistical inefficiencies.Originality/valueTo the best of the authors’ knowledge, this study is among the first to empirically examine the feasibility of postponing SAF blending to the airport level. While existing literature focuses on SAF production and distribution, the concept of downstream blending has not been systematically analyzed. The research provides new insights into how mass customization principles can be applied to SAF supply chains, potentially reshaping fuel logistics in the aviation industry. By identifying critical factors for successful implementation, this study contributes to both academic discussions and practical decision-making in sustainable aviation fuel management.

After decades of fertility postponement, we investigate recent changes in late parenthood across low-fertility countries in the light of observations from the past. We use long series of age-specific fertility rates from the Human Fertility Database (1950-2016) for women, and new data covering the period 1990-2016 for men. In 1950, the contribution of births at age 40 and over to female fertility rates ranged from 2.5 to 9 percent, but then fell sharply until the 1980s. From the 1990s, however, the prevalence of late first births inaeased rapidly, especially so in countries where it was initially lowest This has produced a late fertility rebound in the last two decades, occurring much faster for women than for men. Comparisons between recent and past extremely late (age 48+) fertility levels confirm that people are now challenging the natural fertility barriers, particularly for a first child.

We consider a monopolistic firm selling two substitutable products to a stream of sequential arrivals whose purchase decisions can be influenced by earlier purchases. Before demand realizes, the firm faces a newsvendor problem for the two products with economies of scale in production for each. When consumers are responsive to others’ decisions, social influence amplifies demand uncertainty, leading to a lower profit for the firm. We propose three solutions for the firm to better cope with or even benefit from social influence: influencer recruitment and a reduced product assortment either before demand realization (ex ante) or under production postponement (ex post). First, the firm can offer promotional incentives to recruit consumers as influencers. We reveal an operational benefit of influencer marketing that a very small fraction of such influencers is sufficient to diminish sales’ unpredictability. Second, as the potential substitutability between products increases due to social influence, the firm may leverage the increased substitutability and enjoy lower cost in production by reducing product assortment before demand realization. Last, under production postponement, the firm can take advantage of the way that social influence results in demand herding and reduce product varieties by reacting to preorder information. This paper was accepted by Martin Lariviere, operations management.

The rise in educational enrolment is often cited as a possible cause of the trend to later childbearing in developed societies but direct evidence of its contribution to the aggregate change in fertility tempo is scarce. We show that rising enrolment, resulting in later ages at the end of education, accounts for a substantial part of the upward shift in the mean age at first birth in the 1980s and 1990s in Britain and in France. The postponement of first birth over that period has two components: a longer average period of enrolment and a post-enrolment component that is also related to educational level. The relationship between rising educational participation and the move to later fertility timing is almost certainly causal. Our findings therefore suggest that fertility tempo change is rooted in macro-economic and structural forces rather than in the cultural domain.

Background The postponement of parenthood is a global public health issue that has received attention of many public health experts. However, few studies have investigated the postponement in marriage age, marriage and conception interval, and pregnancy age in terms of demographic and regional heterogenicities. Methods This is a cross-sectional, registry-based study, and a total of 13 894 601 nulliparous couples who participated in the National Free Pre-Pregnancy Check-ups Project and became pregnant during 2013–2019 were included. We calculated annual percentage change and forest plots for marriage age, marriage and conception interval, and pregnancy age. Results Late marriage (marriage age ≥ 35 years), long marriage and conception interval (marriage and conception interval ≥ 2 years), and advanced pregnancy (pregnancy age ≥ 35 years) increased from 1.20%, 22.01%, and 1.88% in 2013 to 1.69%, 32.75%, and 2.79% in 2019, respectively. The corresponding annual percentage changes were 6.55%, 8.44%, and 8.17%. Participants without higher education had a higher annual percentage change, but comparable prevalence for long marriage and conception interval with participants with higher education. Participants residing in second- or new first-tier cities, and the northeast of China who had a higher prevalence of parenthood postponement also had higher corresponding annual percentage changes. Conclusions Structural postponement of parenthood with demographic and regional heterogenicities was observed among Chinese nulliparous couples with planned pregnancies during 2013–2019. Inclusive and comprehensive parenting support should be developed and implemented in mainland China to minimize the negative health effects arising from the postponement, especially for couples without higher education and living in new first/second-tier cities or the northeast China.

Many factors have contributed to the decline in China’s fertility level. Using China’s population census data from 1990, 2000 and 2010, the present study investigates the factors causing the decline in China’s fertility rate by decomposing changes in two fertility indices: the total fertility rate (TFR) and the net reproduction rate (NRR). The change in the TFR is decomposed into the change in the marital fertility rate (MFR) and the change in the proportion of married women (PMW). Four factors contribute to the change in the NRR. The following are the main findings. A drop in the MFR caused a decrease in the TFR and the NRR between 1989 and 2000. However, the change in MFR increased TFR and NRR between 2000 and 2010. Marriage postponement caused a decline in the fertility level between 1989 and 2000 as well as between 2000 and 2010. The effect of the MFR and marriage postponement varied with age and region and also between urban and rural areas.

The article considers the evolution of two “Second Demographic Tradition” (SDT) core characteristics: fertility postponement and the rise of cohabitation, with particular attention being given to the first two decades of the new century. It can be considered as the sequel to the concise overview of the SDT published earlier in the US Proceedings of the National Academy (PNAS) (Lesthaeghe, 2014 ). In the first section, three optimistic views concerning the evolution of fertility are considered: (i) rises due to the end of postponement, (ii) rises connected with advancing human development and (iii) rises associated with advancing gender equality. The focus in this section is mainly but not exclusively on the European experience and its large degree of variation in fertility patterns. It is argued that these three optimistic predictions of sustained fertility rises are mainly based on observations prior to 2010, with too much weight being given to four Nordic countries and too little to other Western European countries with very similar fertility levels. However, these expectations have been thwarted during the second decade, even in the presence of advances in human development and/or gender equality. Hence, the original SDT prediction of 1986 of sustained sub - replacement fertility still holds after 35 years. We expect this to continue during the third decade as well. Furthermore, single-factor explanations are not likely to do justice to far more intricate situations that are responsive to varying structural and ideational influences. In the second section, the evolution of cohabitation is traced in Europe, the USA and Canada, the Latin American countries, three East Asian populations and selected sub-Saharan cases. At the onset, cohabitation can start either from a SDT basis among the better educated or among the poorer classes following a pattern of disadvantage (POD). It is argued that the feature of cohabitation spreads rapidly among all social classes and across all education groups and that in the process of increasing cohabitation, the POD versus SDT argument loses its significance. On a global scale, the rise in cohabitation is contingent on two dimensions: (i) contrasting historical patterns of kinship organisation, including the position of women, and (ii) further advances of the “ethics revolution”, indicating the growing dominance of individual autonomy over traditional societal norms. As a result, no breakthroughs in the near future are expected in countries with a Muslim or Hindu tradition in which no such major cultural shifts have occurred so far.

Childbearing postponement is a key demographic change that has been experienced by most European countries. It leads to a late-fertility pattern, with women realizing their reproductive plans preferentially after the age of 30. This may result in a lower fertility level. Since the ideal family size has not changed in most European countries, it has been argued that the end of the postponement transition further depends on the extent to which the lower fertility of younger women is compensated for by an increase in that of older women. Thus, the completion of the transition depends not only on the formation of a late childbearing pattern, but also on the capability of women to realize their reproductive plans if they commence childbearing later in their lives. This study employed a new approach to assess postponement transition based on analysis of the realization of the fertility intentions of women at later childbearing ages using survey panel data. A method that enables the differentiation between transitional and post-transitional cohorts was applied. The investigation was based on a comparison of the postponement transition in Czechia and France, the former being a post-communist and the latter a Western European country. It was found that despite having a similar pattern of fertility timing, Czechia and France underwent differing phases of postponement transition. The Czech population was identified as being transitional since only the ‘transition’ cohorts had completed their fertility during the period under study. These cohorts did not show a significant increase in realization of fertility intentions in later age. In contrast, the post-transitional French population is characterized by higher completed cohort fertility rates amongst women who entered motherhood at the age of 30 and over and by the significantly higher realization of fertility intentions for women aged 30–34 years.

Background The National Development Plan (NDP) strives that South Africa, by 2030, in pursuit of Universal Health Coverage (UHC) achieve a significant shift in the equity of health services provision. This paper provides a diagnosis of the extent of socio-economic inequalities in health and healthcare using an integrated conceptual framework. Method The 2012 South African National Health and Nutrition Examination Survey (SANHANES-1), a nationally representative study, collected data on a variety of questions related to health and healthcare. A range of concentration indices were calculated for health and healthcare outcomes that fit the various dimensions on the pathway of access. A decomposition analysis was employed to determine how downstream need and access barriers contribute to upstream inequality in healthcare utilisation. Results In terms of healthcare need, good and ill health are concentrated among the socio-economically advantaged and disadvantaged, respectively. The relatively wealthy perceived a greater desire for care than the relatively poor. However, postponement of care seeking and unmet need is concentrated among the socio-economically disadvantaged, as are difficulties with the affordability of healthcare. The socio-economic divide in the utilisation of public and private healthcare services remains stark. Those who are economically disadvantaged are less satisfied with healthcare services. Affordability and ability to pay are the main drivers of inequalities in healthcare utilisation. Conclusion In the South African health system, the socio-economically disadvantaged are discriminated against across the continuum of access. NHI offers a means to enhance ability to pay and to address affordability, while disparities between actual and perceived need warrants investment in health literacy outreach programmes.

Using nineteen panels of the 1979 National Longitudinal Survey of Youth (NLSY-79), we construct life-lines characterizing women’s childless expectations and fertility behavior. One-quarter of women in the NLSY-79 cohort ever reported an expectation for childlessness but only 14.8 percent of women remain childless. Childless women follow two predominant life course paths: (1) repeated postponement of childbearing and the subsequent adoption of a childless expectation at older ages or (2) indecision about parenthood signaled through vacillating reports of childless expectations across various ages. We also find that more than one in ten women became a mother after considering childlessness: an understudied group in research on childlessness and childbearing preferences. These findings reaffirm that it is problematic to assign expected and unexpected childlessness labels to the reproductive experience of childless women. In addition, despite their variability over time, childless expectations strongly predict permanent childlessness, regardless of the age when respondents offer them. Longitudinal logistic regression analysis of these childless expectations indicates a strong effect of childbearing postponement among the increasingly selective group of childless women. However, net of this postponement, few variables commonly associated with childlessness are associated with reports of a childless expectation. We thus conclude that the effects of socio-demographic and situational factors on childless expectations are channeled predominantly through repeated childbearing postponement.