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Birth control pill and other hormonal contraceptives

Oral contraceptives have been used in Canada since 1960 to help prevent unwanted pregnancy. Today the pill is the most popular form of birth control in Canada and the United States, used by nearly 20% of women aged 15–49.

The birth control pill contains manufactured versions of 2 female hormones – estrogen and progesterone. This type of pill is called combined hormone contraception. The hormones work together to prevent pregnancy by inhibiting the release of eggs from the ovary.

  • Our perspective

    The Canadian Cancer Society believes it’s important to understand the risks, benefits and side effects of birth control pills and other hormonal contraceptives so women can make an informed decision about their own health.

    Benefits
    The major benefits of taking hormonal contraceptives:

    • preventing unwanted pregnancy
    • reducing the symptoms of menstruation (cramps and bleeding)
    • reducing the risk of endometrial and ovarian cancers
    • managing the side effects of excessive male hormone production (for example, acne and hair growth)

    Risks
    Women who take the pill have a slightly higher risk for breast, cervical and liver cancers and a higher risk for heart disease and stroke (mostly in women who smoke cigarettes).

    Using oral contraceptives does not appear to have any effect on the risk of colorectal cancer.

    Other types of hormonal contraceptives – such as the patch, vaginal ring, skin implant and injection – are newer, so there’s not enough research yet to assess cancer risk.

    Women who are considering hormonal contraceptives should talk to their doctor about the risks and benefits, their personal and family history and other medical concerns.

  • The pill and breast cancer risk

    A small increased risk of breast cancer has been identified in women who used the birth control pill before their first full-term pregnancy. The risk is smaller for women who used the birth control pill after their first full-term pregnancy.

    According to information provided from the Society of Obstetricians and Gynecologists, for every 10,000 women who use the birth control pill there would be:

    • about 2 additional cases of breast cancer if the pill was used before the first full-term pregnancy
    • about 1 additional case of breast cancer if the pill was used after the first full-term pregnancy

    Other research has shown that 10 years after stopping the birth control pill, a woman’s risk of breast cancer appears to be the same as a woman who never used oral contraceptives.

    Genetics and lifestyle often have a much greater impact on breast cancer risk than taking the birth control pill.

  • The pill and cervical cancer risk

    The risk appears to be greater for developing early stage cervical cancer than it is for more advanced forms of the disease. The recent development of vaccines against cervical cancer and effective cervical cancer screening programs in Canada are important advances in the prevention of cervical cancer and early detection of precancerous and cancerous changes of the cervix.

  • The pill and liver cancer risk

    A history of oral contraceptive use is associated with a small increase in the risk of liver cancer in women who are hepatitis negative. This risk is very rare.

  • The pill and decreased cancer risk

    The birth control pill has been shown to decrease the risk of endometrial and ovarian cancers.

    Endometrial cancer
    The protective effect appears to last for at least 15 years after stopping the pill.

    Ovarian cancer
    The protection offered by the pill is related to the duration of use – the longer a woman uses the birth control pill, the lower her risk of developing ovarian cancer seems to be. The protective effect appears to last at least 20 years after stopping the pill.

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