Progestin-only pills are oral contraceptives taken daily that contain
progestin, a synthetic version of the natural hormone progesterone, but no other
hormones (conventional birth control pills use a combination of two hormones).
Progestin-only pills, or POPs, work by forming a thick mucus barrier across
the cervix that prevents semen from entering the uterus. They also sometime, but
not always, prevent the release of an egg from the ovary.
POPs are often used by breastfeeding mothers as a supplement to the natural
pregnancy prevention that nursing provides. POPs, unlike combination-hormone
pills, do not interact with a woman’s ability to produce milk for her baby.
The benefits and side effects of progestin-only pills are the same as for
combination oral contraceptives. The failure rate, however, is somewhat higher
(about 8% of women will become pregnant within a year with typical use of POPs),
but perfect use can reduce the failure rate to about 1%.
POPs must be taken at the same time each day to maximize protection. Like
oral contraceptives, progestin-only pills do not prevent STDs or HIV/AIDS.
The Patch
A slight variation of the Pill, the Ortho-Evra or ‘the Patch’ is a newcomer
to the birth control market. It contains the same two hormones used in the vast
majority of oral contraceptives—estrogen and progesterone—but delivers them via
a patch that can be attached to the shoulder, buttocks, or hip.
The side effects of the Patch are the same the same as the Pill, with the
addition of possible skin irritation at the patch site.
The major benefit of the Patch vis-à-vis the Pill is that the patient needs
to change it only once a week, compared to the daily requirement of the Pill.
Ortho-Evra is the only birth control patch approved for sale in the United
States, so until a generic version is available, the monthly cost of the Patch
is often higher than the cost of the Pill.
Patients should be aware that, like the Pill, a barrier method (like condoms)
should be used in addition to the Patch to protect against STDs.