When Susannah McIntyre, 37, hauls her three young sons through her Cambridgeshire village, pedestrians mutter, she says. Cafés seem relieved to see them depart. When she was growing up, it was families with five children that seemed big . But at the local primary school, only two other families have three kids. Now she says she feels like an “outlier”, one who is looked down on with suspicion by people “who regard parenting as a self-indulgent lifestyle choice”. Across the world, parenthood is on the wane . In Europe, the only child is becoming the norm, with half of families with dependent children having only one. In the United Kingdom, the figure is 45 per cent, with just 14 per cent of families having three or more. This is repeated in unexpected places. The United Arab Emirates and Tamil Nadu in India now have lower birth rates than Germany. Mexico’s rate has fallen behind the United States, where one-child families now outnumber families with two. Birth rates in more than two-thirds of the world’s countries have fallen below the “replacement rate” of 2.1 children per woman needed to maintain a stable population . The world population will soon start to decline , for the first time since the Black Death of the 14th century, with one estimate putting “peak human” as soon as 2064. There are many factors behind the baby bust. Young people are less likely to be in a relationship than previous generations were at the same age. It is harder for young couples to get on the housing ladder and to feel economically stable enough to contemplate adding a baby to the mix. And some worry whether it would be right to bring a child into a febrile world. But after five years of research, I have come to believe that there is something else at play too: a form of social contagion. In a world that appears to treat parents with hostility, where the advantages of raising children are obscured, remaining childless is easier if the same decision is made by everyone around you. As a phenomenon, it can become self-perpetuating. This extra factor — network effects — can explain the remarkable similarities between falling birth rates across very different places and cultures. It also offers humans a way to reverse the decline by making having children attractive again. Falling birth rates are often presented as a simple matter of choice. But in research of 10 low-fertility countries by Ester Lazzari and Eva Beaujouan, up to half of men and women end their reproductive years wishing they had more children. While passing peak human will ease the burden on natural resources, the drop in global population is projected to be rapid, ushering in legions of elderly who will strain welfare states and economies. In China, where a one-child policy introduced in 1980 distorted family planning for 35 years, there is now the “4-2-1 problem”, with an only child supporting two parents and four grandparents. There are other, subtle effects. As children become less visible, our tolerance for their noisy capriciousness dwindles. In Japan, crowdsourced Dorozoku maps show people how to avoid streets where “children play with balls”. In a smart Paris suburb, judges last year ordered a junior school to close its playground after neighbours complained about noise. At a clinic in Boston, Massachusetts, in 2022, I met Wanda Baker, who had been asked to stand outside because her sick baby and his two siblings were upsetting other patients. “I feel second class,” she said. “Families are society’s most basic unit and humanity’s most indispensable institution,” says Nicholas Eberstadt, demographer and Henry Wendt chair at the American Enterprise Institute. “But as families and their branches thin out, they will become ever less able to bear weight.” Policymakers, he adds, are “not ready for the age of depopulation which will recast societies, economies and power politics”. A low fertility trap Humans copy each other, a primal drive that goes all the way back to our early need to protect ourselves in tribes. Social norms developed as a way to outsource some of our decision-making. Co-operation with the group became instinctive. Even in the modern world, the need to conform is powerful. In an early experiment demonstrating the power of social contagion from the 1950s, the psychologist Solomon Asch asked participants to do a simple task, matching lines on a card, where the correct answer was obvious. Unaware that other participants were actors instructed by Asch, more than a third of participants went along with the group’s choice, despite this being obviously wrong. The impact of network effects on birth rates was well documented by a study in Brazil. The gradual introduction of broadcast signal into different regions in the 1980s was accompanied by a cliff-like fall in birth rates. People with signal had become gripped by telenovelas – soap operas – showing urban female protagonists with few or no kids. In 1960, the average Brazilian woman had just over six children. Forty years later it was just over two: a drop almost as rapid as China’s. The impact was strongest on the female viewers who were closest in age to the female characters, with whom they identified most strongly. More recent studies have corroborated such findings. Research from Sweden in 2010 showed that women working in offices were more likely to have a baby if a colleague of similar seniority did so, with no effect from co-workers at other levels. A separate study of 6,500 German companies similarly found that female employees’ transition rates to first pregnancy roughly doubled after a colleague had a baby, with the effect lasting about two years. The German social scientists Daniel Lois and Oliver Arránz Becker have found that couples’ interest in having a child strengthens if friends become parents. They suggest three possible factors: couples with children demystify parenthood for the network, create a social pressure on others to join them, and create a feeling that not joining might disrupt social ties. “Peer group behaviour signals what people like me are expected to do, and at what point in the life course,” says Anna Rotkirch, research professor at Finland’s Population Research Institute. “We have evolved to be very conscious of reproductive cues in our environment,” she says, adding that she feels these have become increasingly negative. The acceleration of the birth rate fall since the advent of the smartphone may have less to do with time spent on screens distracting from romance and more to do with negative images of childbirth and positive ones about being single. “ Fear of pregnancy and the discourse about motherhood as sacrifice have become more common in the past 15 years,” says Rotkirch, with “many childless women mentioning fear of what happens to your body in childbirth as a reason for not having had a child”. Several studies have found that seeing and holding real babies makes women keener to have their own baby — although they may be self-selecting. Social media increases the extent to which young adults interact with peers or role models they do not know and are not related to. “I have talked to young mothers who are surprised that posting on Instagram about having a baby is creating fewer ‘likes’ than posting about a fancy holiday trip,” says Rotkirch. “Young adults are increasingly taking their reproductive cues from people or platforms with no real interest or stakes in their family formation goals.” The situation today in England and Wales is that women born in 1979 are having smaller families than their baby boomer parents and greatest generation grandparents, while their Gen Z daughters are projected to have even smaller families still. A big reason that people end up with fewer children than they wanted is that we are leaving it later to start a family. European first-time mothers are 31, and fathers 34, compared with 1975 when the average ages were 26 for mothers and 30 for fathers. This in itself makes it harder to have multiple children. But the overarching pattern fulfills the “low fertility trap” hypothesis proposed by the economists Vegard Skirbekk, Wolfgang Lutz and Maria Rita Testa in 2006. They contended that once fertility declines below replacement level, the subsequent shrinking of each generation may entrench childlessness as a norm which becomes harder to reverse. The downward spiral lessens social pressure to have a family. It is true that no country that has fallen well below two children per woman has yet rebounded to anything like that level. South Korea has ticked up a little, from 0.75 in 2024 to 0.8 in 2025, but it’s not yet clear whether that is a temporary phenomenon, a result of women having one child a little younger. As time goes on, a rebound could become less and less possible. In China, the writer Helen Gao has suggested that “none of China’s only children can imagine what raising multiple children could look like”. If you grew up without siblings, and your friends did too, why would you want something different? Add in the absurd demands of modern intensive parenting, and all the other things you can do with your time in the modern world, and it’s no surprise that so many couples now declare themselves “one and done”. Eberstadt, of the American Enterprise Institute, thinks that mimetic theory, the cultural influences on human behaviour, is playing an overlooked role in the baby bust. “The increasing rarity of large families could make it harder for humans to choose to return to having them — owing to what scholars call loss of social learning — and prolong low levels of fertility,” he says. Baby bonus Hopes of filling the demographic gap are often pinned on immigration. But newcomers to a country are also influenced by social norms. In a Norwegian survey, majorities of first-generation immigrants from Vietnam, Pakistan, Sri Lanka and Turkey said that it was very important to have children in order to have a happy marriage. By the second generation, fewer than half expressed this view. Somali-heritage women have an average of seven children in Somalia, but two in Norway. One study has even found that Polish women moving to England and Wales ended up having more children than their peers back home, mirroring the household average of their new country, even though it often costs more to raise a child in London than in Warsaw. Groups that retain stronger ties to their countries of origin, and which have strong religious faith, are less immediately influenced. But the data suggests they still eventually produce smaller families. The fertility rate among Pakistani women in the U.K. dropped by 38 per cent between 2001 and 2021, according to the Migration Observatory. If immigration provides no solution, perhaps network effects themselves can be used. Making children seem desirable, possible and visible is a feature of two companies that are bucking the birth-rate trend in low-fertility countries. In Taiwan, chipmaker TSMC’s employees make up around 0.3 per cent of the population but were parents to 1.8 per cent of Taiwanese babies in 2023. Hsinchu County, where the company is based, has more children per 100 working-age adults than any other region. It has created an environment in which children are highly visible, with wraparound childcare on site and a pre-school on each of its campuses. Canada’s population growth slows to lowest level in 80 yearsErrol Musk: ‘I’m Elon’s father, not his pal’ Similarly LOTTE, the South Korean retail empire, has an internal birth rate which is more than double the national one, at 2.05 babies born per woman compared to 0.8. The company, which employs around 60,000 people, has strong parental leave policies. For example, it is compulsory for fathers to take at least one month of paternity leave on full pay. In recognition of its efforts, the company has been commended by South Korea’s Population Strategy Committee. The pattern can be transposed. In Nagi, a Japanese mountain town, population decline became an existential issue in 2002, when the dwindling number of residents created pressure to merge with other prefectures. The mayor instead worked hard to offer financial incentives including baby bonuses, generous daycare and free healthcare for children. Residents take a whole-community approach, with pensioners stepping in to help out, and children are seen as a positive. The result is that while half of Japanese families have only one child, in Nagi, 47 per cent of households have three or more. Camilla Cavendish is the author of ‘Generation Maybe: Why We’re Having Fewer Children, and What It Means For Us All’ published by Penguin © 2026 The Financial Times Ltd
