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What are the main causes of male infertility?

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Diagram showing the female reproductive system with labeled ovaries, fallopian tubes, uterus, and vagina, alongside hormone pathways and the process from ovulation to fertilization and early embryo development. — infertility Major structures and hormones involved in the initiation of pregnancy. Also seen, at right, is the development of an egg cell (ovum) from follicle to embryo.

Male infertility is a complex medical condition that accounts for approximately one-third of all infertility cases in couples. The primary causes generally involve issues with sperm production, transport, or immunological factors.12

Common Causes of Male Infertility

Sperm Production Deficiencies: Problems with the maturation or quality of sperm are frequent contributors. This includes low sperm count (oligospermia) or the complete absence of sperm in the ejaculate (azoospermia).13
Obstructions: Blockages in the sperm-delivery system or genital tract can prevent the successful transport of sperm.213
Testicular Issues: Conditions such as orchitis (inflammation of the testes, often resulting from mumps), testicular injury, or congenital abnormalities can impair function.213
Varicocele: The enlargement of veins within the spermatic cord, known as a varicocele, is a common cause that can negatively affect sperm quality and quantity.21
Hormonal Imbalances: Abnormally low thyroid or high adrenal secretion can disrupt reproductive function.1
Immunological Factors: The presence of antibodies against sperm, produced by either the male or female, can interfere with fertility.21

Evaluation typically begins with a microscopic examination of the semen to assess sperm count, concentration, motility, and morphology.13