A provocative study from Shizuoka University questions whether today’s fertility level is high enough to sustain human populations over the long term. It argues that a global average of 2.1 births per woman—the traditional replacement rate—may not guarantee stability. Instead, the research suggests a higher threshold of about 2.7 births per woman could be necessary. The findings matter for Thailand, where current fertility sits well below that target.
Historically, experts worried about overpopulation as populations exploded—from under 3 billion in 1960 to over 8 billion today. Public health campaigns, contraception access, and shifting social norms reduced fertility dramatically. By 2023, the world’s average had dropped to around 2.3 births per woman. In many Asian countries, including Thailand, this rapid demographic transition was seen as a development success.
The Shizuoka study notes that the classic replacement rate assumes a stable world with low child mortality and balanced sex ratios. Real life, however, is messier. Not every couple has children, some children don’t survive, and random fluctuations can erase family lines even when average fertility seems sufficient. Using branching-process models, researchers found that unless the average births per woman reach 2.7, the risk of lineages fading away increases markedly.
This isn’t only a theoretical concern. If fertility stays below the true replacement rate, many family lines could gradually disappear, erasing cultural memory, surnames, and traditions. This “quiet fading” is already evident in aging societies with shrinking birth rates and rising elderly populations.
Global trends support caution. As of 2023, two-thirds of the world’s people live in countries with fertility under the old 2.1 replacement rate. Japan is at about 1.3, South Korea around 0.87, and the United States near 1.66. Even nations with strong family-support policies show limited gains, underscoring how complex the issue remains.
Thailand’s situation mirrors these challenges. Data from national and international sources show fertility at roughly 1.3 in 2022, well below historical targets. An aging population intensifies pressures on healthcare, pensions, and economic dynamism. The new study implies that even bold pronatalist policies might not lift fertility to 2.7 unless broader economic and social reforms accompany them.
Biological insights from the research also point to a small, non-prescriptive pattern: populations with slightly skewed sex ratios toward female births may have better long-term persistence under stress. The authors emphasize this is not a directive for social engineering but a reminder that biology and demographics interact in subtle ways.
In practice, Thailand faces multiple barriers to higher birth rates. Urban lifestyles, education, cost of living, housing, childcare access, and work-life balance influence family planning decisions. Thai policymakers are encouraged to address these factors comprehensively—affordable housing, reliable childcare, generous parental leave, and strong gender equity at work—to create an environment where families feel confident about growing.
Culturally, Thailand’s extended family networks and community life have historically supported child-rearing. A sustained decline in birth rates could challenge the transmission of language, rituals, and regional identities that rely on intergenerational exchange. This concern resonates with broader debates about preserving cultural heritage amidst demographic change.
Looking ahead, projections suggest global population momentum may slow after a peak around mid-century, with many economies facing slower growth or decline unless fertility rises. For Thailand, the challenge is not only numbers but ensuring that families can thrive and pass on a vibrant culture to future generations. This requires coordinated policy action that blends economic security with social support for families.
The takeaway for Thai readers is clear. Decisions about family size have far-reaching implications beyond personal choice. They influence cultural continuity, community life, and national resilience. Public dialogue, targeted family-friendly reforms, and a holistic approach to social and economic policy can help Thailand navigate demographic transitions while safeguarding heritage.
In summary, the study invites policymakers to rethink population targets in a holistic way—balancing demographic sustainability with cultural vitality. For Thailand, that means creating a society where families feel empowered to raise children, knowing that their decisions contribute to a thriving, culturally rich nation.
Note on sources: Data and perspectives are integrated from research and national statistics agencies, along with global demographic analyses. Where applicable, institutional findings are referenced in context to illustrate real-world implications for Thailand.