Final answer:
Close to 4 million American women use IUDs primarily for contraception. These devices are effective and reversible, with a low failure rate and a return to normal fertility upon removal. The correct answer is a. contraception.
Step-by-step explanation:
It is estimated that close to 4 million American women use IUDs for contraception. An IUD is a T-shaped device that is inserted into the uterus to prevent pregnancy. The two main types of IUDs are the copper IUD and the hormonal IUD, such as the Mirena, also known as an intrauterine system (IUS), which releases progestin. This hormone works by thickening cervical mucus to prevent sperm from reaching an egg, interfering with ovulation, and affecting the lining of the uterus to inhibit implantation should fertilization occur.
IUDs are highly effective, with failure rates less than one percent, and they are equally effective with typical use as with perfect use. They are among the most widely used forms of reversible contraception due to their effectiveness. However, IUDs can cause increased menstrual bleeding and more painful cramps, with a small risk of uterine perforation. Despite these risks, fertility typically returns to normal immediately after the IUD is removed.
The correct answer to the multiple-choice question is a. contraception, as IUDs are primarily used for this purpose and not for thyroid problems or menstrual flow.