Birth rates across the world have been falling dramatically for decades, sparking political debate and economic concern in many countries. But new research suggests the reasons behind the global fertility decline are far more complex than commonly assumed. According to an analysis discussed in New Scientist, the most important factors shaping family decisions today may not be purely economic but deeply rooted in social support systems, modern lifestyles and changing expectations about parenting.
The scale of the decline is striking. At its peak in 1963, the global fertility rate averaged 5.3 births per woman. Today it has dropped to around 2.2, close to the level required to maintain stable populations. In many developed countries, however, fertility rates have fallen well below the replacement rate of about 2.1 children per woman. Nations such as the United Kingdom, the United States and Australia report rates between 1.4 and 1.6, while Japan has about 1.2 births per woman and South Korea has one of the lowest rates in the world at roughly 0.75.
Public discussion about this trend often focuses on familiar explanations, including the high cost of childcare, housing shortages, and women’s participation in the workforce. But cognitive and evolutionary anthropologist Paula Sheppard of the University of Oxford argues that these broad explanations miss the deeper social dynamics behind family planning decisions. In an interview with New Scientist, Sheppard explained that looking only at national fertility statistics overlooks the diversity of experiences among different groups of people.
Traditional demographic studies tend to analyze entire populations and attempt to forecast long-term trends. Sheppard’s work instead focuses on individual decision-making. Her research investigates why people delay starting families and why many ultimately have fewer children than they say they want.
To explore this question, Sheppard conducted a study in the United Kingdom that combined qualitative interviews and experimental surveys. Participants took part in focus groups where they discussed the factors influencing their decisions about having children. These conversations included both men and women, as men are often excluded from discussions about fertility decisions.
From these discussions, Sheppard identified several key factors that people consider when planning families, including housing stability, relationship security, and support from relatives and friends. She then used a method known as a discrete choice experiment, commonly used in fields such as health economics and transport research, to examine how people prioritize these factors.
Participants were asked to evaluate different scenarios involving trade-offs between conditions such as housing quality, partner involvement, financial security and social support. Because the experiment was conducted online, the study was able to gather responses from a large, nationally representative sample.
The results revealed that while financial issues such as housing and childcare costs matter, they are often not the most decisive factors. Instead, the strongest influence on whether people want to have children is the availability of social support. Participants consistently emphasized the importance of having a reliable partner, supportive relatives, or a broader network of friends and community members who could help raise children.
According to Sheppard, this finding reflects a fundamental aspect of human evolution. Humans are what anthropologists call cooperative breeders, meaning that raising children historically involved extended families and community members rather than just parents alone. Unlike many other species, human mothers have often raised several dependent children at the same time with help from fathers, grandparents and social networks.
Modern urban lifestyles, however, have weakened these support systems. Many people live far from relatives, work long hours and lack the community networks that once helped families share childcare responsibilities. As a result, raising children can feel far more demanding than it did in previous generations.
The study also revealed differences between social groups. People without university degrees often focused on housing quality and neighborhood conditions, expressing concerns about raising children in crowded areas without green space or good schools. In contrast, highly educated women placed greater emphasis on having partners who would actively share parenting responsibilities.
For many women with higher education, the decision to delay having children is closely linked to career considerations. Women often face greater career interruptions after childbirth, and many prefer to wait until they feel secure in their professional lives before starting a family. This delay can reduce the total number of children they ultimately have.
Interestingly, the research found that most people still aspire to have two or three children. In the United Kingdom, however, only about two babies are born for every three that people say they would ideally like. Much of this gap appears to be caused by delays in starting families, which shorten the window in which couples can have multiple children.
The study also highlighted changing expectations among men. Highly educated men often expressed a desire for flexible working arrangements, including the ability to work from home or take parental leave. These preferences reflect growing interest in more active fatherhood and shared parenting responsibilities.
Despite growing concern about falling birth rates, Sheppard believes public discussion often exaggerates the risks. With the global population approaching nine billion people, she argues that humanity is not facing an immediate population collapse. However, she also believes that many people who want children struggle to have the families they envision due to structural barriers.
While governments around the world have introduced policies such as childcare subsidies and financial incentives to encourage births, their impact has generally been limited. Even countries with generous family policies, including France and several Nordic nations, still have fertility rates below replacement level.
According to Sheppard, there is no single policy solution to reverse declining birth rates. Instead, she argues that societies need to rethink how work and family life are organized. In modern economies, workplaces and childcare responsibilities are often treated as separate and competing domains, a structure that makes parenting more difficult.
Sheppard suggests that addressing the fertility decline will require making work and family life more compatible. As highlighted in the New Scientist interview, creating environments where parenting responsibilities can coexist with careers and social life may be more important than financial incentives alone in shaping the future of global birth rates.
