SummaryBackgroundPopulation estimates underpin demographic and epidemiological research and are used to track progress on numerous international indicators of health and development. To date, internationally available estimates of population and fertility, although useful, have not been produced with transparent and replicable methods and do not use standardised estimates of mortality. We present single-calendar year and single-year of age estimates of fertility and population by sex with standardised and replicable methods.MethodsWe estimated population in 195 locations by single year of age and single calendar year from 1950 to 2017 with standardised and replicable methods. We based the estimates on the demographic balancing equation, with inputs of fertility, mortality, population, and migration data. Fertility data came from 7817 location-years of vital registration data, 429 surveys reporting complete birth histories, and 977 surveys and censuses reporting summary birth histories. We estimated age-specific fertility rates (ASFRs; the annual number of livebirths to women of a specified age group per 1000 women in that age group) by use of spatiotemporal Gaussian process regression and used the ASFRs to estimate total fertility rates (TFRs; the average number of children a woman would bear if she survived through the end of the reproductive age span [age 10–54 years] and experienced at each age a particular set of ASFRs observed in the year of interest). Because of sparse data, fertility at ages 10–14 years and 50–54 years was estimated from data on fertility in women aged 15–19 years and 45–49 years, through use of linear regression. Age-specific mortality data came from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 estimates. Data on population came from 1257 censuses and 761 population registry location-years and were adjusted for underenumeration and age misreporting with standard demographic methods. Migration was estimated with the GBD Bayesian demographic balancing model, after incorporating information about refugee migration into the model prior. Final population estimates used the cohort-component method of population projection, with inputs of fertility, mortality, and migration data. Population uncertainty was estimated by use of out-of-sample predictive validity testing. With these data, we estimated the trends in population by age and sex and in fertility by age between 1950 and 2017 in 195 countries and territories.FindingsFrom 1950 to 2017, TFRs decreased by 49·4% (95% uncertainty interval [UI] 46·4–52·0). The TFR decreased from 4·7 livebirths (4·5–4·9) to 2·4 livebirths (2·2–2·5), and the ASFR of mothers aged 10–19 years decreased from 37 livebirths (34–40) to 22 livebirths (19–24) per 1000 women. Despite reductions in the TFR, the global population has been increasing by an average of 83·8 million people per year since 1985. The global population increased by 197·2% (193·3–200·8) since 1950, from 2·6 billion (2·5–2·6) to 7·6 billion (7·4–7·9) people in 2017; much ...

The Islamic Republic of Iran has experienced a remarkable demographic transition over the last three decades. As a result of social, demographic and economic changes, Iran’s fertility declined from 7.0 births per woman in 1980 to around 1.8 to 2.0 in 2011 based on our estimation (McDonald et al. 2015). The initial rise and rapid fall of fertility accompanied by a decline of child mortality led to a post-revolutionary youth bulge in the age distribution that will lead to rapid ageing in the longer-term future. Others have argued that Iran’s fertility has fallen to much lower levels - as low as 1.5 births per woman (eg. Erfani 2013). Such low estimates led to the Government of Iran adopting a pronatalist policy with the aim of increasing fertility, although the components of the policy are still under discussion. Different views have been expressed on the role of family planning and other programs in meeting population policy goals in Iran in the future with some advocating the discontinuation of government assistance to family planning. This paper aims to review the trends and levels of fertility, marriage, and family planning and their implications for policy. Using various datasets and detailed parity-based measures of fertility, the dynamics of fertility regulation practiced by Iranian couples are investigated. Our findings suggest that contraceptive use stabilized before 2000 and postponement of the first child and wide birth intervals are the main contributors to the level of fertility. Therefore, instead of discontinuation of the family planning program, policy to sustain fertility at its present level or a little higher needs to focus upon improving the economic circumstances of young people so that they are able to make less constrained choices about family formation than is the case at present.

Successful aging is an interdisciplinary concept. Despite the great body of literature on successful aging, few studies have focused on its subjective and multidimensional measurements. Thus, the present study aimed to develop an instrument to measure selfperceived successful aging. Methods: We used a mixed method approach. The successful aging dimensions were explored through an integrative review and qualitative study among 64 older adults. Based on the obtained qualitative data, initial item pool was designed and its content validity was evaluated. A quantitative survey among 600 older adults and exploratory factor analysis was applied to test the structural validity of the instrument. Results: The EFA results indicated that the instrument loaded into seven factors; "psychological well-being", "social support", "financial and environmental security", "spirituality", "physical and mental health", "functional health", and "health-related behavior". In addition, the instrument had a high degree of reliability coefficients. Discussion: The obtained results indicated methods of measuring successful aging, as well as the importance of generating social policy in the area of aging well; researchers should consider all dimensions of successful aging at individual and social levels.

Sustained below replacement fertility leads to declining population size. Several countries in Asia have experienced below replacement fertility for many years. The paper applies a novel approach to examining the viability of using immigration to achieve zero population growth in six Asian countries: China, Japan, Republic of Korea, Thailand, Singapore and Australia. The novel approach is to estimate the level of immigration that would be required to maintain a constant annual number of births in the long term. Maintaining the number of births at the current level is the fastest way to achieve eventual zero population growth. A population with a constant annual number of births, labeled as a quasi-stationary population, also has a near-to constant age structure that is not excessively old. The study concludes that, for all countries except Australia, no reasonable level of immigration could produce a quasi-stationary population if fertility remains at the country's 2020 level. The constraining factors are the current population size and level of fertility and the extent to which there is acceptance of permanent immigrants in the country. If fertility were to increase over 15–20 years to 1.7 births per woman and the country was accepting of relatively large numbers of permanent immigrants, the quasi-stable outcome becomes potentially viable for all countries except China.