Progestin-only birth control methods do not contain estrogen. The methods can be used by women who cannot take estrogen or by women who are breast-feeding. They work by changing a woman’s menstrual cycle, which may result in changes in menstrual flow and frequency of periods, as well as an increase in breakthrough bleeding. Over time, users of progestin-only methods report having no periods at all. Progestin-only methods may also lead to slight weight gains (approximately 4 to 5 pounds over 5 years of use), feelings of bloatedness, and/or breast tenderness. These problems are typically the most frequent reason for discontinuing usage.

minipills or POP (progestin-only pill)

A type of birth control pill that contains only synthetic progesterone and no estrogen.

Minipills

Earlier in this chapter we discussed combined-hormone pills, which work by inhibiting ovulation and thickening cervical mucus. Minipills, or POPs (progestin-only pills), work the same way, but they can be used by women who smoke or are breast-feeding and have fewer side effects than combined-hormone pills.

Minipills are more expensive and slightly less effective (92% for typical use; 99.7% for perfect use) than combination pills, require obsessive regularity in pill-taking, and can cause irregular bleeding (Hatcher, 2004). Women who get pregnant while taking minipills have a higher rate of ectopic pregnancy compared to women taking combined – hormone pills. In addition, minipills are less likely to be stocked by pharmacies.

subdermal contraceptive implant

Contraceptive implant that time-releases a con­stant dose of progestin to inhibit ovulation.