The overall human fertility rate has been continuously declining across the globe for a number of reasons. This review summarizes data, which proposes that the use of disposable diapers for newborns and infants may incur reproductive harm in adulthood. More than 70 years ago, a disposable synthetic waterproof baby diaper was developed, mainly to reduce the burden of working mothers. Modern diapers feature the same original design, which contains one unit of disposable material wrapped around the perineum to collect urine and feces. This design results in an increase in internal area temperatures by 2-4 °C, which can be detrimental to the function and development of reproductive cells. Moreover, the standard diaper template promotes the free passage of feces, including fecal bacteria, to the genitals, which can lead to urogenital infection and reproductive impairments. The available clinical data suggest that diaper use during infancy may have a negative impact on fertility after puberty. There is a critical need for additional studies to better assess the impact of diapers on reproductive health.