1. Evolution, Survival, and the Modern Demographic Paradox

Approximately three hundred thousand years ago, the first groups of *Homo sapiens* roamed the valleys and savannas of Africa. Their lives unfolded within nomadic bands of hunter-gatherers, for whom the primary imperative was securing daily sustenance. During various periods of the Middle and Upper Paleolithic, the species was subjected to severe biological and climatic bottlenecks that brought it to the brink of extinction. Despite these adversities, the development of symbolic language, social cohesion, and the capacity for technological innovation enabled humans to progressively master and transform their environment, eventually establishing themselves as a biologically thriving and expansive species.

Throughout the 19th and 20th centuries, the consolidation of modern medicine, the discovery of antimicrobials, the development of mass immunization programs, and the implementation of environmental sanitation networks fostered an unprecedented epidemiological transition. The sustained decline in both general and infant mortality caused life expectancy at birth to skyrocket, sparking deep demographic concern by the mid-20th century regarding imminent global overpopulation and the eventual depletion of the planet's resources.

In response to these Malthusian projections, various governments and international bodies implemented policies aimed at birth control. The most emblematic example was the one-child policy instituted in the People's Republic of China in the late 1970s. Simultaneously, in the Western world, the advent and widespread availability of hormonal and barrier contraceptives radically transformed social structures by effectively decoupling the experience of sexuality from reproductive function. Compounding this phenomenon was women's progressive access to higher levels of education and their full entry into the labor market. The convergence of these factors led to an accelerated decline in global fertility rates; currently, many countries fall below the generational replacement threshold (estimated at 2.1 children per woman), creating a landscape characterized by rapid aging and a shrinking productive base within society.

2. The vulnerability of the mother-child dyad and the safeguarding of perinatal health

Amidst declining birth rates, the survival and holistic well-being of every newborn have acquired cardinal strategic and bioethical importance. Maternal and child health—and the preservation of the mother-child dyad—constitute the foundation for the demographic continuity and socioeconomic development of nations. Protecting this dyad requires timely, universal, and prevention-oriented prenatal care aimed not only at mitigating immediate obstetric risks but also at safeguarding the neurodevelopment and quality of life of future generations.

However, structural gaps in healthcare systems and the fragmentation of primary care have fostered the resurgence or persistence of preventable conditions that severely compromise fetal and neonatal development. Notable among these are vertically transmitted infectious diseases and congenital endocrine disorders; while the diagnostic and therapeutic approaches for these conditions are well-established, they remain frequently underutilized:

Congenital syphilis: Caused by the spirochete *Treponema pallidum*, this condition serves as a critical indicator of failures in the coverage and quality of prenatal care programs. Neglect regarding serial serological screening and the failure to provide early treatment with benzathine penicillin to pregnant women continue to result in pregnancy loss, stillbirth, prematurity, and long-term disabling sequelae (such as bone lesions, sensory deficits, and central neurological damage).

Hepatitis C (HCV) and vertical transmission: Despite the therapeutic revolution brought about by direct-acting antivirals (DAAs), the persistence of perinatal HCV infection highlights regulatory gaps in routine antenatal screening protocols for at-risk populations, thereby depriving mothers and children of timely interventions to prevent hepatic fibrosis and the progression to chronic disease at an early age. Congenital hypothyroidism: This is one of the most common preventable causes of intellectual disability and neurodevelopmental delay in pediatrics. A lack of consolidation, universal coverage, and the immediate reporting of results within neonatal metabolic screening programs leads to irreparable delays in initiating levothyroxine replacement therapy, thereby compromising the infant's cognitive potential.

3. Final considerations: a public health imperative.

Ensuring the viability of future generations goes beyond quantitative demographic discourse; it requires securing the health and well-being of offspring. It is paradoxical and unacceptable that, in an era dominated by precision medicine and biotechnological innovations, we continue to see debilitating sequelae from conditions for which early detection and curative or replacement treatments are widely standardized globally.

Reevaluating and strengthening sexual health programs, perinatal screening, and the systematic monitoring of vertically transmitted infections is an urgent imperative for social justice and public health. Only through a rigorous preventive approach—grounded in epidemiological evidence and universal coverage—will it be possible to offer future citizens a productive life path, free from pathological burdens that should have been overcome decades ago.

1. Harari YN. *Sapiens: De animales a dioses. Una breve historia de la humanidad*. Barcelona: Debate; 2014.

2. Vollset SE, Goren E, Yuan CW, Cao J, Smith AE, Hsiao T, et al. Fertility, mortality, migration, and population scenarios for 195 countries and territories from 2017 to 2100: a forecasting analysis for the Global Burden of Disease Study. *Lancet*. 2020;396(10258):1285–1304.

3. World Health Organization. *Global guidance on criteria and processes for validation: Elimination of mother-to-child transmission of HIV, syphilis and hepatitis B virus*. Geneva: World Health Organization; 2021.

4. Korenromp EL, Rowley J, Alonso M, Mello MB, Wijesooriya NS, Mahiané SG, et al. Global burden of maternal and congenital syphilis and associated adverse birth outcomes—Estimates for 2016 and progress since 2012. *PLoS One*. 2019;14(2):e0211720.

5. Indolfi G, Easterbrook P, Dusheiko G, El-Sayed MH, Jonas MM, Thorne C, et al. Hepatitis C virus infection in children and adolescents. *Lancet Gastroenterol Hepatol*. 2019;4(6):477–487.

6. Rose SR, Wassner AJ, Winter WE, Addo OY, Moltz KC, Poceviciute I, et al. Congenital hypothyroidism: Screening and management. *Endocr Pract*. 2023;29(8):645–660

Hernández-Bautista PF, Securing the Future: Demography, Perinatal Health, and the Challenge of Preventable Conditions, ERSJ 2026,2(2) 73-75.