Mini-pill (progestin only)

Effectiveness: 87 to 99.7 percent (effectiveness is near 100 percent if the pill is taken daily as directed; because many women do not use as directed, the pregnancy rate is 2-9 pregnancies per 100 women each year, and it may be slightly less effective if you’re overweight).

What is it? Progestin-only birth control pills contain a synthetic hormone similar to the progesterone produced by your body. They come in packs containing 28 pills, 21 of which are active and 7 that serve as “reminder” pills. They must be taken daily at the same time of day to keep hormone levels even. Birth control pills are often referred to as “the pill” or oral contraception. The majority of women taking the pill use combination estrogen/progestin pills, but the progestin-only option is better for some women.

How does it work? Mini-pills release synthetic progestin that keeps you from releasing eggs so pregnancy cannot occur. The hormones also thicken your cervical mucus and affect the lining of the uterus, both of which may help prevent pregnancy.

STD protection: No; you will still need to use condoms if you are concerned about STDs.