Vegard Skirbekk

Spending time outdoors provides opportunities for physical activity, exposure to natural light, and social contact. Although young people’s time use has changed substantially in recent decades, little is known about long-term trends in adolescents’ outdoor engagement. This question is especially important because adolescence is a period of major life transitions and the development of lasting behavioral habits. This study examines 20-y trends in time spent outdoors among American adolescents using time-diary data from 14,235 individuals aged 15 to 19 in the 2003–2023 American Time Use Survey, a nationally representative survey of the US population. We describe trends in outdoor exposure and examine associations between outdoor time and leisure behaviors, including computer use for leisure, indoor physical activity, and time spent with friends. We find that outdoor engagement among boys has declined sharply, erasing a long-standing male advantage and causing boys’ participation levels to converge with girls’ at similarly low rates. Greater time spent in computer-based leisure was associated with less outdoor time, particularly among boys, whereas time spent with friends was positively associated with outdoor engagement for both sexes. Indoor physical activity did not change over the observation period and did not offset declines in outdoor time. These findings suggest that broader changes in leisure activities may be reshaping how young people engage with outdoor environments. Further research is needed to better understand the factors underlying these trends and their potential long-term implications.

Religious leaders have unique potential to motivate individuals and governments to address climate change. Nevertheless, there is currently a lack of systematic information on religious leaders’ views of climate change and their willingness to raise awareness and encourage climate mitigation behaviors. We present results from an exploratory global survey of Muslim religious leaders ( N = 150 from 29 countries; e.g., imams, religious teachers, students of religious seminaries). Nearly all respondents agreed that the climate is changing (98.6%), and about half agreed that climate change is mainly or entirely caused by humans (48.7%). Nearly half (48.0%) agreed that climate change is already substantially harming people. Most respondents indicated that Muslim religious leaders and the Muslim religious community should do more to address climate change, and that Islam offers a set of values and principles that motivate environmental protection and climate action. Respondents reported that they sometimes addressed climate change and other environmental topics in their religious work. They reported high willingness to support government spending on technologies that curb emissions and the effects of climate change; the implementation of new technologies to promote greener production and consumption; and reductions in consumption. There was lower willingness to promote dietary changes and reduced meat consumption; vegetarianism; or limits on population growth and family size. These preliminary findings suggest that, although many respondents are not regularly addressing climate change in their religious work, Muslim religious leaders may have substantial potential to promote climate change awareness and action.

Background and ObjectivesCentral and general adiposity have been linked to dementia risk, but their relation to blood-based Alzheimer disease (AD) biomarkers is unclear. We examined life course adi...

Women's and men's equal participation in work, education, and politics rests upon widespread public support for gender equality. While notable increases in support for gender equality over the past decades have been celebrated, existing evidence is limited by a predominant focus on Western societies. Utilizing data from the World Values Survey and European Values Study covering 78 countries that represent >86% of the global population, we examine how population-level support for gender equality in the public sphere changed between 1995 and 2022, both globally and across different cultural and socioeconomic contexts. Our results indicate that, although public support for gender equality increased in most countries, it stagnated in the global population as a whole. Moreover, there has been a pronounced and increasing divergence across countries, particularly between Western and non-Western societies. We attribute part of the stagnation in global public support for gender equality to demographically induced compositional effects. Namely, we find that (i) changes in the national composition of the global population have constrained increases in global public support for gender equality; (ii) fertility is higher in countries where average support for gender equality is lower; and (iii) fertility is higher and occurs earlier among women with less egalitarian views. Given that parents typically transmit their gender-related views to their children, higher and earlier fertility among persons with less egalitarian views has likely constrained global growth in gender egalitarianism. We call for a closer examination of how demographic processes influence global trends in gender egalitarianism.

Reproductive-age populations show a growing male surplus around the globe as a consequence of declining mortality, narrowing sex differences in mortality, and sex-selective abortions in some countries. Population structures are important determinants of marriage markets and childbearing. In this study, we estimate the past, current, and future difference between the male and the female total fertility rates around the world using an established indirect demographic approach drawing on data from the UN World Population Prospects. Our results indicate a crossover from historically higher male fertility to increasingly higher female fertility, which occurs globally in 2024. This shift is not toward parity, but rather reflects a growing disparity driven by the increasing male surplus at reproductive ages, which exerts downward pressure on male fertility rates relative to those of women. The difference is expected to grow to up to 20% in countries like China and India, where sex-selective abortion has reinforced sex imbalances in population structures. Overall, we highlight the growing sex inequalities in reproduction and call for more research on sex differences in fertility.

This study documents the concentration of childbearing to later reproductive ages, analyzing global patterns of fertility postponement from 1950 to 2040. We study late fertility (ages 30+) and very late fertility (ages 35+) trends at the global, subregional, and national levels using data for all countries and areas of the world since 1950 and historical data for eleven countries dating to 1850. The analysis reveals a significant shift toward late fertility in developed regions only, with fertility increasingly occurring after age 30. Globally, more than one out of three births in 2023 occurs to women aged 30 and above, compared to only one in four in 1990. Historical comparisons indicate similar late fertility patterns in pre‐demographic transition populations and early industrialized societies. The share of childbearing at age 35 among those aged 30 and above is, however, not universally increasing with declining fertility. The study identifies substantial regional disparities in late fertility trends, with some regions maintaining stable late fertility timing despite changes in total fertility levels.

Background: Childbearing postponement in high-income countries has likely led to an increase in the incidence of age-related infertility. While assisted reproductive technologies (ART) can help some individuals to become parents, this often takes time. However, we know little about how long it takes individuals with infertility problems to achieve a live birth, whether they use ART or not, and how this has changed over time. Method: We use retrospective information from the HUNT study, which provides rare information on the age at first conception attempt among people who have ever experienced infertility issues. These data are linked to the Norwegian Medical Birth Registry (NMBR), which allows tracking the timing of live births and whether they result from ART. We control for several maternal and paternal characteristics and distinguish between the late 1980–1990s (1987–99) and the 2000–2010s (2000–19). Cox models were fitted to samples of 863 mothers and 590 fathers. Results: The average time from the start of conception attempt to spontaneous births is three years, and to ART births is five years. ART births occurred faster when pregnancy attempts were initiated in 2000–19 rather than 1987–99 (coeff = 0.536, [0.198; 0.873] for women, coeff = 0.487, [0.072; 0.902] for men), and when men and women tried to conceive for the first time at age 35–39 (coeff = 1.215, [0.260; 2.171] for women, coeff = 1.005, [0.275; 1.735] for men). This was not the case for spontaneous births. Conclusions: While assisted reproductive technologies enable individuals facing infertility issues to achieve a live birth, they require more time to succeed. However, since the 2000s, time to ART births has decreased, with the shortest observed among those initiating conception attempts in their late thirties. Despite the fact that age remains a significant negative factor associated with the declining occurrence of births, these findings may reflect shifts in the profile of fertility clinic patients, faster care-seeking processes, and improvements in ART efficiency.

This paper argues for the reintegration of mortality into studies of fertility transition by using net reproduction measures rather than solely focusing on total fertility rates ( TFR ). Accounting for mortality through metrics like the 2-Sex Net Reproductive Rate ( 2SNRR ) would change our understanding of fertility transitions globally. Using global data for 236 countries (1950–2023), the analysis shows that the 2SNRR -based fertility transitions typically occur later, at lower peak levels, and with less dramatic declines than TFR -based assessments suggest. This difference is particularly pronounced in regions with high mortality rates, such as parts of Africa and Southern Asia. The study reveals that seven countries have yet to begin their fertility transitions when mortality is considered, challenging the notion that fertility decline is universal. Incorporating mortality into fertility analyses provides a more nuanced understanding of demographic transitions and has important implications for population policies and the degree to which current and historical reproductive patterns differ from net replacement levels.