For the past 75 years in global public health, one of the major priorities has been exponential population growth and Malthusian concerns that the supply of food on the planet won’t be able to keep up. In 1951, the world’s population was 2.5 billion, which increased to 4 billion by 1975, 6.1 billion by 2000, and 8 billion by 2023. Governments in the two most populous countries, India and China, even implemented, respectively, draconian policies such as forced sterilisation and a one-child restriction. It now seems that many nations have switched to worrying about the opposite problem. Findings published last month from the Global Burden of Disease study, which examines epidemiological trends across the world, notes that fertility rates are falling in most countries. This can be seen as a public health success: lower fertility rates tend to reflect fewer children dying in the first 10 years of life, and an environment that protects women’s bodily autonomy and access to birth control, as well as girls’ education. Having mainly planned pregnancies is seen as societal progress. But if low fertility is sustained, as the Global Burden of Disease study discusses, population decline follows roughly a generation later. In 2021, 110 countries were below replacement-level fertility. By 2050, the authors estimate population numbers will be falling in 155 countries. The problem is that with ageing populations, economies will struggle to have enough young workers to take up necessary jobs and to pay taxes and social security. Yet the problem of low fertility isn’t true for every part of the world: sub-Saharan Africa’s population is expected to keep growing. That region will have too many young people, and the rest of the world will have too few. One rational response to this demographic imbalance is for countries in population decline to encourage immigration from Africa. Does it matter where people come from, as long as they want to contribute to the workforce of a country and assimilate themselves and their children into the community? Aren’t we all human? The immigration solution has faced pushback. For instance, the Hungarian prime minister, Viktor Orbán, has said, “Migration for us is surrender.” If you feel uncomfortable with this notion of a growing black or brown population, it’s worth asking what exactly this disquiet is about: skin colour? External appearance? Fear of another culture, or religion, taking over? The other proposed solution has been trying to encourage people to have more children: some countries have launched marketing campaigns encouraging people to have children while others have offered financial incentives. In Taiwan, a presidential candidate suggested giving people a free pet if they have a baby, while Italy and Greece have offered per-child baby bonuses. Since 2006, the South Korean government has invested $270bn (£214bn) into social and economic programmes encouraging higher fertility. So far, none of these efforts seem to have made fertility rates rise. In fact, South Korea’s birthrate fell to a new record low in 2023. There are clear obstacles to address, such as the cost of raising a child (including childcare, food, education, clothes), the negative financial impacts of taking parental leave, the huge time-investment of being an unpaid carer, including sleep deprivation – and the anxiety of bringing a child into an uncertain world, grappling with the climate crisis, war and conflict. While public policy interventions have been used in an attempt to tackle some of the factors putting off potential parents, no one seems to have come up with a programme that can reverse the overall trend. The basic fact is that women now have a choice that they didn’t have in previous generations: socially, it’s now acceptable and feasible, with widespread birth control, to decide against child-raising. Studies have shown that women who are unmarried and childless are the happiest subgroup in the population. In addition, research indicates that people who don’t have children tend to report higher life satisfaction; in short, “having children is bad for quality of life … until they move out” (of course this picture becomes more complicated depending on the specific demographic and individual interviewed). While it’s clear that there’s a concerning demographic trend in decreasing fertility, seeing it only as a failure of public policy would be wrong. Lower fertility reflects the success of women’s education and equal employment, gender equality, access to contraceptives and options, and people being able to make choices based on the kind of happy life they want to live. But it’s also true that if people want to have children, governments should remove the financial and practical blocks that often make it an impossible choice. So far, however, even extensive support hasn’t put any rich country back on track to grow its population in the future. This means we must think about immigration as a solution, too, including tackling where resistance to immigration comes from – and how to have a nuanced and balanced debate without making racial concerns the focal point. Prof Devi Sridhar is chair of global public health at the University of Edinburgh