The review discusses the decline in sperm parameters in the 21st century, attributing it to factors such as obesity, lifestyle, and environmental toxins. It highlights the impact of endocrine-disrupting chemicals (EDCs), including pesticides, bisphenol A, phthalates, and heavy metals, on male fertility. The World Health Organization (WHO) has updated its manual for semen analysis, reflecting changes in normal sperm parameters over the years. The review also examines the effects of smoking, alcohol, recreational drugs, stress, and poor sleep on sperm quality. Environmental pollution, including air pollution, is linked to reduced sperm quality, particularly in terms of morphology. Obesity and metabolic syndrome are significant contributors to male infertility, with mechanisms involving hormonal imbalances, increased scrotal temperature, and toxin accumulation. The review emphasizes the role of oxidative stress in impairing sperm parameters, with ROS and OS affecting sperm function and DNA integrity. Radiofrequency radiation from mobile phones is also discussed as a potential factor in reduced sperm quality. Overall, the review underscores the complex interplay of various factors affecting male fertility and the need for further research to understand and mitigate these issues.The review discusses the decline in sperm parameters in the 21st century, attributing it to factors such as obesity, lifestyle, and environmental toxins. It highlights the impact of endocrine-disrupting chemicals (EDCs), including pesticides, bisphenol A, phthalates, and heavy metals, on male fertility. The World Health Organization (WHO) has updated its manual for semen analysis, reflecting changes in normal sperm parameters over the years. The review also examines the effects of smoking, alcohol, recreational drugs, stress, and poor sleep on sperm quality. Environmental pollution, including air pollution, is linked to reduced sperm quality, particularly in terms of morphology. Obesity and metabolic syndrome are significant contributors to male infertility, with mechanisms involving hormonal imbalances, increased scrotal temperature, and toxin accumulation. The review emphasizes the role of oxidative stress in impairing sperm parameters, with ROS and OS affecting sperm function and DNA integrity. Radiofrequency radiation from mobile phones is also discussed as a potential factor in reduced sperm quality. Overall, the review underscores the complex interplay of various factors affecting male fertility and the need for further research to understand and mitigate these issues.