Strong social networks predict higher fertility rates in new study

Communities where people report high levels of social support and frequent social interactions tend to have higher birth rates, regardless of their economic status. This pattern suggests that strong social networks within a region may help sustain population levels even as birth rates decline globally. The findings were published in the journal Biodemography and Social Biology.

Birth rates are dropping across much of the developed world. Several nations are approaching what demographers call lowest-low fertility, defined as fewer than 1.3 children per woman. This shift is drastically altering population pyramids and economic forecasts worldwide. Finland currently faces this steep decline, dropping from a fertility rate of 1.87 in 2010 to 1.30 in 2025.

This rapid downward trend has challenged the assumption that robust social welfare programs naturally protect against falling birth rates. Finland offers paid parental leave, heavily subsidized childcare, and home care allowances. Yet, its fertility rate has fallen faster than in many neighboring countries.

Researchers often look to economic conditions, such as recessions or housing costs, to explain why people choose to have smaller families. Economic indicators alone do not fully explain recent demographic shifts, particularly in Nordic countries where financial safety nets are strong. As a result, demographers are searching for alternative explanations. Family formation is an inherently social process, leading scientists to investigate how social environments influence childbearing.

Social capital broadly refers to the networks, resources, and shared norms that exist within a community. Previous research on family planning usually focused on the individual level, testing whether a specific person’s network of friends and relatives encouraged them to have children. Less is known about how the overall social atmosphere of a geographic region impacts its aggregate birth rate.

Eetu Soini, a psychology researcher at the University of Helsinki, led a team to investigate this gap in the literature. The researchers wanted to see if community-level measures of social cohesion corresponded to regional variations in fertility. Finland exhibits substantial regional differences in birth rates, with lower numbers in the southeast and higher numbers in the northwest coastal areas. The team hypothesized that municipalities with stronger social ties would report higher birth rates.

Soini and his colleagues analyzed data from a large national health survey conducted between 2012 and 2017. The survey included 100,750 adults across 299 Finnish municipalities. The researchers used this data to calculate regional estimates for seven different components of social capital. These components included perceived social support, frequency of social interactions, community participation, cultural engagement, general trust, trust in people, and loneliness.

To measure social support, the survey asked participants who they believed truly cared about them and who would provide practical help if needed. For social interactions, participants reported how often they communicated with people outside their household in person, by phone, or online. The researchers used a statistical technique to mathematically adjust the survey responses so they would accurately reflect the true age and sex demographics of each specific municipality.

The team then compared these localized social metrics to municipality-level fertility data spanning from 2018 to 2020. They incorporated a three-year lag between the survey data and the birth records to see if existing social conditions preceded current fertility trends. The researchers used spatial statistical models to account for the fact that neighboring regions often share similar demographic traits. By using these spatial models, the researchers could filter out hidden variables that cluster geographically.

The team adjusted their models for population size, population density, religious affiliation, and a composite score of regional socioeconomic status. The socioeconomic score combined local data on tax income, education levels, and unemployment rates.

The researchers found that municipalities with higher levels of expected social support had higher total fertility rates. Regions where residents reported more frequent social interactions also saw higher birth rates. These associations remained even after adjusting for all demographic and socioeconomic variables.

The specific source of the social support did not change the main outcome. Support expected from romantic partners, relatives, friends, and other associates were all linked to higher regional birth rates. The local socioeconomic status, by contrast, showed no association with fertility rates in any of the models.

The study also analyzed specific age groups to see who was most sensitive to these regional social factors. The link between social support and higher fertility was strongest for individuals between the ages of 20 and 39. The association peaked specifically among people in their twenties.

The researchers suggest that young adults often face more uncertainty in their careers and finances. This precariousness might make a supportive social environment especially relevant for their transition to parenthood. Older age groups may already have established careers and stable incomes, making them less reliant on broader community support.

Not all forms of social capital were linked to birth rates. The researchers found no association between a region’s fertility rate and its levels of general trust or trust in people. Community participation, such as involvement in sports clubs, health organizations, or political groups, was also unrelated to fertility. Engagement in cultural events and regional rates of loneliness similarly showed no association with birth rates. These null findings suggest that the recent rise in public loneliness may not be a driving force behind demographic changes.

The researchers performed additional calculations to ensure that people simply delaying childbirth did not skew the results. Demographers call this a tempo effect, where the average age of mothers giving birth rises and temporarily depresses the annual birth rate. Even after adjusting for changes in the average age at birth, the regions with higher social support from relatives and more frequent social interactions still demonstrated higher fertility rates.

The study relies on cross-sectional data, meaning it captures a snapshot of a population at a specific time. This design prevents researchers from determining whether high social capital directly causes people to have more children. It is entirely possible that the reverse is true, where a higher birth rate fosters greater social cohesion. Having children often connects parents to new community networks, such as schools, daycares, and youth sports leagues, which could increase overall regional interactions.

Comparing broad regional metrics does not always perfectly mirror individual behavior. A regional correlation between social support and fertility might reflect community-wide norms that encourage family growth, or it could simply be the mathematical sum of individual choices. Future research will need to separate individual influences from neighborhood effects to better understand how local environments shape family planning. Investigating how social capital affects the decision to have a first child versus subsequent children could also provide more specific insights into these population trends.

The study, “Regional social capital and fertility rate: Municipality-level analysis in Finland,” was authored by Eetu Soini, Kateryna Golovina, Hans Hämäläinen, Anna Rotkirch, Venla Berg, Suvi Parikka, and Markus Jokela.