Birth control pills, skin patches, and vaginal rings
contain estrogen and progestin. There are also progestin-only birth control
pills, implants (Implanon), and shots (Depo-Provera). Hormonal methods of birth
control prevent eggs from being released from the ovaries, thicken cervical
mucus to prevent sperm from entering the uterus, and thin the lining of the
uterus to prevent implantation.
Hormone pills come in packs, with each pack
containing 3 weeks of hormone pills. During the fourth week, when you do not
receive hormones, you have a menstrual period. (One type of birth control pill
is sold in 84-day packs, for fewer periods per year.)
The hormone patch releases estrogen and progestin through your
skin for 7 days. Over a 4-week period, you use one patch per week for 3 weeks,
then no patch for 1 week. During this week, you have a menstrual period. You
can wear the patch on your lower abdomen, upper torso (not breasts), buttocks,
or upper arm.
The hormone vaginal ring is placed in the vagina
for 3 weeks. This gives you continuous birth control for the month. On the
first day of the fourth week, you remove the ring. You then have a menstrual
period. The exact position of the ring in the vagina is not critical for the
ring to work.