Britannica Sources used in this answer

How can a problem with sperm movement lead to infertility?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

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.

In the context of male infertility, a problem with sperm movement—referred to as low motility—is a significant factor that can prevent successful fertilization.12

Healthy sperm rely on their flagellum, or tail, to whip and undulate, providing the necessary movement to travel through the female reproductive tract to reach the egg. If sperm lack the ability to move effectively, they cannot navigate the reproductive tract or reach the egg in time to fertilize it before their energy supplies are exhausted.3

Motility is a key metric assessed during semen analysis, where clinicians look for a sufficient percentage of motile sperm to ensure a high probability of conception. Factors such as advancing age can naturally lead to the production of less-motile sperm, while other underlying health issues or genetic factors may also impair this essential function. When sperm cannot reach the egg, the fundamental process of sperm-egg association cannot occur, resulting in infertility.2134