Which of the following describes an IUD's mechanism of action?

An IUD, or intrauterine device, primarily functions by preventing sperm from fertilizing an egg. It achieves this through a combination of mechanical and biochemical methods. The presence of the IUD in the uterus creates an environment that is hostile to sperm, thereby reducing their ability to reach and fertilize an egg.

While some hormonal IUDs do release hormones that can affect ovulation, the primary and defining feature of all IUDs is their ability to prevent fertilization. This distinction differentiates it clearly from options that focus solely on ovulation prevention or hormonal balance.

Understanding the mechanism of IUDs is crucial for anyone studying reproductive health, as it highlights how this form of contraception operates effectively to prevent pregnancy through non-hormonal means or localized hormone release. This mechanism underlines the significance of IUDs in providing contraceptive options and informs discussions surrounding reproductive choices and family planning.