The birth control pill (also called "the Pill") is a daily pill that contains hormones
to change the way the body works and prevent pregnancy. Hormones are chemical
substances that control the functioning of the body's organs. In this case, the hormones
in the Pill control the ovaries and the uterus.
How Does It Work?
Most birth control pills are "combination pills" containing a mix of the hormones
estrogen and progesterone to prevent ovulation (the release of an egg
during the monthly cycle). A woman cannot get pregnant if she doesn't ovulate because
there is no egg to be fertilized.
The Pill also works by thickening the mucus around the cervix, which makes it difficult
for sperm to enter the uterus and reach any eggs that may have been released. The
hormones in the Pill can also sometimes affect the lining of the uterus, making it
difficult for an egg to attach to the wall of the uterus.
How Is the Pill Taken?
Most combination pills come in either a 21-day pack or a 28-day pack. One hormone
pill is taken each day at about the same time for 21 days. Depending on your pack,
you will either stop taking birth control pills for 7 days (as in the 21-day pack)
or you will take a pill that contains no hormones for 7 days (the 28-day pack). A
woman has her period when she stops taking the pills that contain hormones. Some women
prefer the 28-day pack because it helps them stay in the habit of taking a pill every
There is also a type of combination pill that decreases the frequency of a woman's
period by supplying a hormone pill for 12 weeks and then inactive pills for 7 days.
This decreases the number of periods to one every 3 months instead of one every month.
Another kind of pill that may change the number of monthly periods is the
low-dose progesterone pill, sometimes called the mini-pill. This
type of birth control pill differs from the other pills in that it only contains one
type of hormone — progesterone — rather than a combination of estrogen
and progesterone. It works by changing the cervical mucus and the lining of the uterus,
and sometimes by affecting ovulation as well. The mini-pill may be slightly less
effective at preventing pregnancy than combination pills.
The mini-pill is taken every day without a break. A girl who is taking it might
have no period at all or she may have irregular periods. For the minipill to
work, it must be taken at the same time every day, without missing any doses.
Any type of birth control pill works best when it is taken every single day
at the same time of day, regardless of whether a girl is going to have sex. This is
especially important with progesterone-only pills.
For the first 7 days of taking the Pill, a girl should use an additional form of
contraception, such as condoms, to prevent pregnancy. After 7 days, the Pill should
work alone to prevent pregnancy. This timing can vary based on the type of Pill and
when you start taking it — so be sure to talk about it with your doctor. Also,
it's important to continue using condoms
to protect against sexually
transmitted diseases (STDs).
If pills are skipped or forgotten, a girl is not protected against pregnancy and
she will need a backup form of birth control, such as condoms. Or she will need to
stop having sex for a while. Do not take a friend's or relative's
How Well Does It Work?
Over the course of 1 year, about 9 out of 100 typical couples who rely on the Pill
to prevent pregnancy will have an accidental pregnancy. Of course, this is an average
figure and the chance of getting pregnant depends on whether you take your birth control
pills every day. The Pill is an effective form of birth control, but even missing
1 day increases the chance of getting pregnant.
In general, how well
each type of birth control method works depends on a lot of things. These include
whether a person has any health conditions or is taking any medicines or herbal supplements
that might interfere with its use (for example, an herb like St. John's wort can affect
how well the Pill works). Talk to your doctor to check if anything you take could
affect how the Pill works for you.
How well a particular method of birth control works also depends on whether the
method chosen is convenient — and whether the person remembers to use it correctly
all the time.
Protection Against STDs
The birth control pill does not protect against STDs. Couples
having sex (or any intimate sexual contact) must always use condoms along with
the Pill to protect against STDs.
decision to not have sex or any intimate sexual contact) is the only
method that always prevents pregnancy and STDs.
Possible Side Effects
The birth control pill is a safe and effective method of birth control. Most young
women who take the Pill have none to very few side effects. The side effects that
some women have while on the Pill include:
irregular menstrual bleeding (more common with the mini-pill)
nausea, headaches, dizziness, and breast tenderness
blood clots (rare in women under 35 who do not smoke)
Some of these side effects improve over the first 3 months on the Pill. When a
girl has side effects, a doctor will sometimes prescribe a different brand of the
The Pill also has some side effects that most girls are happy about. It usually
makes periods lighter, reduces cramps, and is often prescribed for women who have
Taking the combination Pill often improves
acne, and some doctors prescribe it for this purpose. Combination birth control
pills have also been found to protect against some forms of breast disease, anemia,
ovarian cysts, and ovarian and endometrial cancers.
Who Uses It?
Young women who can remember to take a pill each day and who want excellent protection
from pregnancy use birth control pills.
Not all women can — or should — use the Pill. In some cases, medical
or other conditions make the use of the Pill less effective or more risky. For example,
it is not recommended for women who have had blood clots, certain types of cancers,
or some migraine
headaches. It also might not be recommended for girls who have had unexplained
vaginal bleeding (bleeding that is not during their periods) or who think they might
Girls who are interested in learning more about different types of birth control,
including the Pill, should talk to their doctors or other health professionals.
How Do You Get It?
A doctor or a nurse practitioner (NP) must prescribe the Pill. He or she will ask
about a girl's health and family medical history, and do a complete physical exam,
which might include a pelvic
exam. If the doctor or NP prescribes birth control pills, he or she will explain
when to begin taking the Pill and what to do if pills are missed.
The doctor or NP will usually ask the girl to come back in a few months to
have her blood pressure checked and to see if she is having any problems.
After that, girls who are having sex should get routine exams every 6 months to
a year, or as recommended.
How Much Does It Cost?
The Pill usually costs between $0 and $50 a month, depending on the type. Many
health and family planning clinics (such as Planned Parenthood) sell birth control
pills for less. In addition, birth control pills and doctor visits are covered by
many health insurance plans.