Global human fertility rates have been steadily declining, driven by a combination of environmental, lifestyle, genetic, and disease-related factors. We propose that an additional, underexplored contributor may be the widespread use of disposable diapers during infancy, with potential long-term effects on reproductive health.

Disposable diapers, introduced over 70 years ago, retain a largely unchanged design: a synthetic, waterproof absorbent layer enclosing the perineal region. This configuration has been shown to elevate local temperatures by approximately 2-4°C. Such thermal increases may adversely affect the development and function of germ cells, which are known to be sensitive to heat stress. During infancy, a critical period of rapid somatic and germ cell proliferation, elevated temperatures may induce apoptosis in developing testicular cells, potentially impairing future spermatogenesis.

Evidence from conditions such as cryptorchidism supports the vulnerability of germ cell maturation to temperature. Disruption of the transition from gonocytes to spermatogonia under elevated thermal conditions can result in long-term reproductive impairment. However, the specific impact of sustained, moderate scrotal warming during infancy on adult fertility remains insufficiently studied.

Additionally, early infancy is characterized by a transient surge in testosterone (“mini-puberty”), coinciding with rapid brain development. We hypothesize that increased scrotal temperature could influence testicular endocrine function during this critical window, with possible downstream effects on neurodevelopment, including gender-related brain differentiation. Furthermore, diaper design may facilitate the transfer of fecal microbiota to the urogenital tract, increasing the risk of urinary tract infections (UTIs), which are common in infants. The long-term reproductive consequences of early-life UTIs remain unclear.

In summary, current evidence suggests that diaper use may have previously unrecognized implications for reproductive and developmental health. Further longitudinal and mechanistic studies are needed to evaluate these potential risks.

Eliezer Girsh (Ph.D.), clinical embryologist and andrologist was graduated (M.Sc. and Ph.D.) in Reproduction by Hebrew University of Jerusalem and by Weizmann Science Institute (Post Doctorate), Israel. Dr. Girsh has experience from 1988 in the leading IVF laboratories and continuing education in field of Human Reproduction. Dr. Girsh is an emeritus-director of IVF laboratory at Barzilai Universital Medical Centre, Ashkelon, and director of Andrologic laboratories at Cryobank and Male Fertility Center (MFC), participates in all aspects of planning and supervisory activities within the laboratory. Dr Girsh is also CEO of ELNAT Reproduction, providing a wide profile of services in ART. Dr. Girsh is involved in commercial and clinical projects around the world. Dr Girsh has authored many scientific articles on reproduction and infertility, authored and edited “A Textbook of Clinical Embryology” (Cambridge University Press, 2021).