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Expert Report on the Socio-Scientific Causes of the Increase in Out-of-Wedlock Births and the Transformation of Traditional Family Structures

I. The New Demographic Reality: A Global Overview of Family Transformation

This report explores the key drivers behind the rise in out-of-wedlock births and the fundamental transformation of traditional family structures, viewed through a socio-scientific lens. Globally, two interconnected phenomena are observed: a steady decline in marriage rates and a sharp increase in non-marital birth rates. These trends reflect a shift in societal norms for family life, where marriage and parenthood are becoming decoupled.

The Decoupling of Marriage and Parenthood: Global Trends

In many developed countries, marriage rates have been in steady decline since the mid-20th century. For instance, the annual marriage rate in the United States in the 1920s was double what it is today.1 This trend was accelerated during the COVID-19 pandemic, with marriage rates plummeting by an average of 25% across several OECD countries in 2020.2 Concurrently, the rate of out-of-wedlock births has surged. In 1970, out-of-wedlock births were less than 10% in most OECD countries, but by 2020, this figure had risen to over 30% in most nations and more than half in some.1 In the U.S., the proportion of out-of-wedlock births jumped from 11% to nearly 41% over the four decades from 1970 to 2010.3 These figures suggest that the decline in marriage has not necessarily led to a rejection of partnerships themselves. Rather, it reflects a shift toward other forms of relationships, such as cohabitation. For example, the proportion of women worldwide who were married or in a cohabiting union only saw a slight decrease from 69% in 1970 to 64% in 2024.1 This phenomenon highlights that the traditional institution of marriage is no longer considered a prerequisite for parenthood.

Geographic and Socio-Demographic Variations

Out-of-wedlock birth rates vary enormously by country and region, demonstrating the influence of cultural and socioeconomic contexts on this phenomenon. In approximately 25 countries, including China, India, and most nations in North Africa and Western and Southern Asia, the rates are very low, typically below 1%.4 In these societies, non-marital births still face strong social disapproval.4 In stark contrast, another 25 countries, primarily in Latin America, including Brazil, Chile, Costa Rica, and Jamaica, have out-of-wedlock birth rates exceeding 60%.4 Similarly, in developed nations like Belgium, Denmark, Norway, and Sweden, non-marital births have become a common occurrence.4 Beyond these international differences, significant variations exist within countries. Taking the United States as a case study, the national average for out-of-wedlock births was 40% in 2014, but this figure varied greatly among racial and ethnic groups: 29% for whites, 53% for Hispanics, and 71% for blacks.4 This disparity underscores the importance of socioeconomic factors, which will be discussed later in the report. Table 1: Global and Regional Status of Out-of-Wedlock Births and Cohabitation Rates (2014-Present) Region/Country Out-of-Wedlock Birth Rate (2014) Proportion of Children with Cohabiting Parents (2005-2014) OECD Countries Less than 10% (1970) → Exceeds 30% (2020) 10% (2005) → 15% (2014) Latin America (25 countries) Exceeds 60% Not available China, India, North Africa (25 countries) Less than 1% Not available United States (National Average) 40% Not available United States (Whites) 29% Not available United States (Hispanics) 53% Not available United States (Blacks) 71% Not available

II. The Shifting Social and Cultural Landscape

The rise of out-of-wedlock births is not merely a statistical phenomenon but a reflection of a profound change in social norms and values. This change is rooted in the decline of the stigma associated with non-marital parenthood, which has fundamentally reshaped social perceptions of having children outside of marriage.

The Decline of Stigma: From Social Pariah to New Norm

Historically, societal attitudes toward out-of-wedlock births were overwhelmingly negative. Before the 1970s, unmarried pregnant women were often "pariahs, banished from schools, ostracized by their peers or scurried out of town to give birth in secret".5 This intense social disapprobation was a major barrier to non-marital parenthood. However, attitudes shifted significantly by the 1990s. The New York Times reported that young mothers were now "supported and embraced" in their decision to have and raise a child.5 This change was more than a simple shift in attitude. Historical evidence suggests that unmarried mothers and their children faced not only social stigma but also material disadvantages, as the stigma made it difficult to find suitable employment, housing, childcare, and emotional support.6 Therefore, the decline of the stigma also involved a change in the social and economic conditions that made non-marital parenthood a less precarious option. This cultural shift enabled the social viability of the phenomenon, making it a complex and multifaceted process rather than a mere change in attitude.

The Paradoxical Trend in Public Opinion

Despite the long-term trend of declining stigma, recent public opinion polls show a paradoxical turn. Even as cohabitation and non-marital births become more common, a growing number of Americans now view these trends as "a bad thing for society".7 For example, the percentage of U.S. adults who believe a single woman raising a child alone is bad for society rose from 40% in 2018 to 47% in 2021, and a similar negative view of cohabitation increased from 19% to 24%.7 This shift does not necessarily represent a return to past moral condemnation. Instead, it signals the emergence of a new form of social concern. Research indicates that children in single-parent homes are more likely to face poverty and other hardships 3, and single mothers faced particular difficulties during the COVID-19 pandemic.8 This suggests that public perception has shifted from moral judgment to a practical concern about the real-world challenges—such as economic, social, and health issues—that these family forms face. This nuanced understanding prevents a simplified view of the issue and offers a deeper insight into the problem. Table 2: Changing American Views on Cohabitation and Single-Parent Child Rearing (2018 vs. 2021) Group Percent who say cohabitation is "bad for society" (2018 vs. 2021) Percent who say single-mother child rearing is "bad for society" (2018 vs. 2021) U.S. adults (total) 19% → 24% 40% → 47% Men 19% → 26% 50% → 59% Women 19% → 23% 30% → 37% White adults 20% → 25% 41% → 49% Black adults 24% → 32% 46% → 46% Aged 18-29 10% → 13% 32% → 42% Republicans 30% → 38% 53% → 62% Democrats 10% → 13% 30% → 36%

III. Key Socio-Economic Drivers of Family Change

The transformation of family structures is driven not only by cultural changes but also by deep-seated economic forces. Economic instability and increased female autonomy are key socioeconomic factors that have redefined the traditional economic role of marriage.

Economic Precarity and Delayed or Forgone Marriage

The economic insecurity of young adults is a major factor in the decline of marriage rates. Research shows that indicators of economic stability such as employment, high wages, and homeownership are directly linked to marriage rates.9 Marriage is seen as a "financially committed relationship," and men are less likely to marry if they are unemployed or have no savings.10 Additionally, unlike in the past, the economic characteristics of both men and women are now considered important in the decision to marry.9 This financial emphasis aligns with the trend in developed nations for many young people to prioritize education and career development before starting a family.11

Women's Economic Independence and Bargaining Power in the Family

The rise in women's educational attainment and economic autonomy has fundamentally altered family dynamics. Historical examples in the U.S. of "Married Women's Property Acts" and "Earnings Acts" show that women's increased economic independence significantly raised divorce rates.12 This occurred because women, having a "better fallback option" outside of marriage, gained more power to end an unsatisfying relationship. This principle also applies to marriage formation. As women's economic power has grown 12, they feel less pressure to accept traditional, unequal marital arrangements. They may choose to delay marriage to pursue a career 11 or opt for cohabitation, which offers a different type of commitment than marriage.13 This shift means that marriage is being redefined as a voluntary partnership between economic equals or near-equals, changing the social contract of marriage itself.

Cohabitation: A Functional Alternative Showing Social Class Stratification

Cohabitation has emerged as a viable alternative for parenthood, as evidenced by the rising proportion of children living with cohabiting parents in OECD countries.4 However, this phenomenon is marked by a significant social class stratification, a concept referred to as "diverging destinies".13 For women with less education, cohabitation is increasingly serving as a "viable context for childbearing and child-rearing," effectively replacing traditional marriage.13 In contrast, for highly educated couples, it tends to still function as a precursor to marriage. This dual role highlights a deepening social class divide in family behavior.

IV. The Influence of Law and Public Policy

Changes in family life have been profoundly influenced by legal and policy shifts, not just socioeconomic forces. Legal developments related to reproductive rights and the promotion of individual autonomy have played a key role in undermining traditional family norms.

The 'Reproductive Technology Shock'

The increased availability of contraception and the liberalization of abortion laws in the late 1960s and early 1970s created a "reproductive technology shock" that reverberated through society.5 This shock "eroded the custom of 'shotgun marriage'".5 Previously, the threat of an unwanted pregnancy compelled men to propose marriage. With the advent of new technologies, women were less likely to demand a promise of marriage in the event of pregnancy, and men felt less pressure to get married if a pregnancy occurred.5 This is a direct sociological cause of the rise in out-of-wedlock births. This cultural shift was reinforced by the legal framework. U.S. Supreme Court cases reflected and solidified these changes. The Griswold v. Connecticut case (1965) granted married couples the right to contraception, and Eisenstadt v. Baird (1972) extended this right to unmarried individuals, legally codifying the separation of sex from marriage.14 The court ruled that the constitutional right to privacy "inhere[s] in the individual, not the marital couple" 14, a foundational legal shift that mirrored and amplified the social changes of the era.

The Complex and Sometimes Paradoxical Effects of Policy

Public policy can have unintended consequences. Many people expected that liberalized abortion and contraception would reduce out-of-wedlock births, but the decline of the shotgun marriage custom led to the opposite effect.5 Interestingly, some studies show a contrary effect. Abortion restriction laws, such as waiting periods or limits on Medicaid funding, have been associated with a decrease in a state's non-marital birth rate.15 It is hypothesized that these laws may lead unmarried women to reduce unprotected sexual activity or increase contraceptive use to avoid unwanted non-marital pregnancies.15 This illustrates how policy can indirectly change behavior and influence demographic outcomes.

V. A Nuanced Perspective on Children and Family Structure

The relationship between family structure and child development is not a simple issue, and it is complex to conclude that "traditional families are better." Sociological research consistently shows that the impact of family structure on a child's life is not direct but is mediated by a host of other factors.16

Decoupling Causation: Structure Versus Process

While research shows that children of married parents often have better physical, emotional, and academic well-being, the link between family structure and child outcomes is not a direct causal relationship.16 Instead, the "advantage" of married-parent households is largely mediated by their socioeconomic status.19 Studies have found that the better outcomes observed in children of married couples are primarily due to these families having higher incomes, parental education levels, and a lower likelihood of being racial/ethnic minorities.19 For example, children in households with an income of $100,000 or more were half as likely to be held back a grade as children in households with an income of less than $25,000.19 This indicates that the key drivers of child development are not family structure itself, but the resources and environment associated with that structure. Table 3: The Mediating Effect of Socioeconomic Status on the Relationship Between Family Structure and Child Development Family Type Child Academic Outcome (Grade Retention Rate) Median Household Income (U.S., 2000) Other Factors Heterosexual Married Parents Lowest $58,000 Most racially/ethnically advantaged (22.9% Black or Hispanic) Gay Male Couples Normal levels $50,000 41.6% Black or Hispanic Lesbian Couples Normal levels $47,000 37.1% Black or Hispanic Households with income < $25,000 12.6% <$25,000 Not available Households with income > $100,000 5.3%

$100,000 Not available

The Importance of Family Dynamics and Resources

What truly matters for a child's well-being are family dynamics and resources, such as parental mental health, financial stability, and the quality of parent-child relationships, rather than family structure.16 The difference in outcomes between children in intact and non-intact families is small, and most children from non-traditional families grow up to be competent, well-functioning adults.16 Furthermore, children in any type of family are far more likely to have normal development than those living in institutions like orphanages or shelters.19 This highlights the importance of the family environment, regardless of its form.

VI. Conclusion: A Synthesis of Interacting Factors and Future Trajectories

The increase in out-of-wedlock births and the transformation of family structures are not the result of a single factor. They are the outcome of a complex interplay of changing social norms, economic realities, and legal frameworks. The decline of social stigma, the economic independence of women, the financial precarity of young adults, and expanded access to reproductive technologies are all key drivers of these changes. This analysis has important implications for policymakers. Policies that simply "promote marriage" may be ineffective if they fail to address the underlying socioeconomic factors—such as economic instability, high housing costs, and a lack of childcare options—that make marriage difficult for many people. Ultimately, the reality of new family forms should not be seen as a societal collapse but as an adaptation to modern conditions. The focus of future research and policy should not be on forcing a return to a traditional model but on ensuring that all family forms have the resources and support necessary to foster the well-being of both parents and children. 참고 자료 Marriages and Divorces - Our World in Data, 9월 4, 2025에 액세스, https://ourworldindata.org/marriages-and-divorces SF3.1: Marriage and divorce rates | OECD Family Database, 9월 4, 2025에 액세스, https://webfs.oecd.org/els-com/Family_Database/SF_3_1_Marriage_and_divorce_rates.pdf Marriage, Parenthood, and Public Policy - Brookings Institution, 9월 4, 2025에 액세스, https://www.brookings.edu/articles/marriage-parenthood-and-public-policy/ Out-of-Wedlock Births Rise Worldwide | YaleGlobal Online, 9월 4, 2025에 액세스, https://archive-yaleglobal.yale.edu/content/out-wedlock-births-rise-worldwide An analysis of out-of-wedlock births in the United States | Brookings, 9월 4, 2025에 액세스, https://www.brookings.edu/articles/an-analysis-of-out-of-wedlock-births-in-the-united-states/ Top of the Campops: 60 things you didn't know about family, marriage, work, and death since the middle ages - Cambridge Group for the History of Population and Social Structure, 9월 4, 2025에 액세스, https://www.campop.geog.cam.ac.uk/blog/2025/01/30/non-marital-births/ More Americans now see single motherhood, cohabitation as bad ..., 9월 4, 2025에 액세스, https://www.pewresearch.org/short-reads/2022/03/11/rising-share-of-americans-see-women-raising-children-on-their-own-cohabitation-as-bad-for-society/ Is Support for Single Motherhood and Cohabitation Falling in the U.S.?, 9월 4, 2025에 액세스, https://ifstudies.org/blog/is-support-for-single-motherhood-and-cohabitation-falling-in-the-us For Young Adults, Economic Security Matters for Marriage - U.S. Census Bureau, 9월 4, 2025에 액세스, https://www.census.gov/library/stories/2018/06/millennial-marriages.html Living in precarious partnerships: Understanding how young men's ..., 9월 4, 2025에 액세스, https://pubmed.ncbi.nlm.nih.gov/40071818/ Countries with Late Marriages: Why Don't They Rush? - Zamin.uz, 11.08.2025, 9월 4, 2025에 액세스, https://zamin.uz/en/world/156894-countries-with-late-marriages-why-dont-they-rush.html Married Women's Economic Independence and Divorce in the ..., 9월 4, 2025에 액세스, https://www.cambridge.org/core/journals/social-science-history/article/married-womens-economic-independence-and-divorce-in-the-nineteenth-and-earlytwentiethcentury-united-states/C7B2E5AF671D89BE19670E2E8CB4F0B3 Cohabiting Couples in the United States Are Staying Together Longer but Fewer Are Marrying - PRB.org, 9월 4, 2025에 액세스, https://www.prb.org/resources/cohabiting-couple-staying-together-longer/ Eisenstadt v. Baird | 405 U.S. 438 (1972) | Justia U.S. Supreme ..., 9월 4, 2025에 액세스, https://supreme.justia.com/cases/federal/us/405/438/ Nonmarital births and state abortion policies - PubMed, 9월 4, 2025에 액세스, https://pubmed.ncbi.nlm.nih.gov/20818592/ Family structure, child outcomes and environmental mediators ..., 9월 4, 2025에 액세스, https://aifs.gov.au/research/research-reports/family-structure-child-outcomes-and-environmental-mediators Family Structure and Children's Health, 9월 4, 2025에 액세스, https://ifstudies.org/blog/family-structure-and-childrens-health/ The impact of family structure on the health of children: Effects of divorce - PMC, 9월 4, 2025에 액세스, https://pmc.ncbi.nlm.nih.gov/articles/PMC4240051/ Nontraditional Families and Childhood Progress Through School ..., 9월 4, 2025에 액세스, https://pmc.ncbi.nlm.nih.gov/articles/PMC3000058/