Which statement about intrauterine devices for contraception is correct?

• A. They have no systemic effect on hormones.
• B. They are not safe for long-term use.
• C. They may cause uncomfortable intercourse.
• D. They never spontaneously expel.

Answer: (A)

Intrauterine devices (IUDs) primarily provide a local mechanism of action in the uterine environment to prevent pregnancy. The hormonal IUD, for instance, releases a low dose of progestin locally, which minimizes systemic exposure and effects. This localized action is key to understanding why the statement about having no systemic effect on hormones is correct. While hormonal IUDs can have some systemic absorption, the overall impact on hormonal levels is much less significant compared to other hormonal contraceptives like oral contraceptives or hormonal implants. As a result, they are often favored in situations where avoiding systemic hormonal effects is desired, such as in women who may have contraindications to estrogen.

Regarding the other options: while IUDs are generally considered safe for long-term use, they can be expulsion or displacement risks. Some users may experience discomfort during intercourse, but this varies widely among individuals. It is also possible for an IUD to spontaneously expel, particularly during the first few months of insertion or if proper placement has not been achieved, which undermines the idea that they never spontaneously expel. Thus, the focus on their localized hormonal effect distinguishes the correct statement.