1. Congenital Factors • Genetics: a key factor—male chromosome abnormalities and Y-chromosome AZF microdeletions affect sperm development, causing low count, azoospermia, or abnormal sperm. • Congenital genital malformations: e.g., penile defects, micropenis, severe hypospadias, preventing intercourse or sperm entry; testicular dysplasia causes sperm-generation disorders.

2. Acquired Factors • Genital infection: bacteria inflame glands, lower secretion and spermatogenesis, change sperm shape, reduce motility/survival, and impair fertilization; most patients have orchitis, epididymitis, prostatitis, urethritis. • Varicocele: the most common factor, mainly age 20–30; raised scrotal temperature and metabolites may impair sperm. • Bad habits: smoking, alcohol, staying up late, obesity, saunas lower sperm density, directional motility, and raise abnormality. • Occupational/environmental: testes need 35.5–36.5°C; prolonged >1–2°C above body (drivers, cooks, welders) impairs spermatogenesis; radiation, heavy metals, electromagnetic exposure (e.g., chemical-plant workers, long-haul drivers) harm sperm.

In summary, male infertility has identifiable causes; address them with a doctor's help. (More info: QR code or 181-0136-5219.)