Two of the most important types of hormones that control reproduction are estrogens and progestins. Birth control pills are made from synthetic estrogens and/or progestins. Experiments have shown that these hormones cause women’s breast cells to divide more rapidly. Cells which divide more rapidly are more prone to develop into cancer cells.
In 2005, the World Health Organization classified oral contraceptives as a Group I carcinogen—the most dangerous classification known. Also, a comprehensive meta-analysis published in the Mayo Clinic Proceedings in October, 2006 found that 21 out of 23 retrospective studies done since 1980 showed that women who took oral contraceptive prior to the birth of their first child sustained a 44% average increased risk of developing pre-menopausal breast cancer, “This risk rose to 52% for women who took the pill for at least four years prior to the birth of their first child.”
Breast cancer is the most common cause of cancer death in U. S. in women age 20-59. In the U.S. about 211,000 women are diagnosed annually and over 40,000 die from this disease Research studies show that breast cancer risk is almost tripled for women who used Depo-Provera for 2 years or more before age 25.
Natural Family Planning (NFP) methods are available which use no chemicals or surgery and cause no increase in breast cancer risk. Not to be confused with the rhythm method, NFP is based on observations of a woman’s cervical mucus and (for some methods) other symptoms as well. One of the largest research studies of NFP (involving 19,843 women and performed in India by the World Health Organization) showed a pregnancy rate of 0.2 pregnancies per 100 women yearly.
- Anderson T, Battersby S, et al. Oral contraceptive use influences resting breast proliferation. Hum. Pathol. 1989; 20: 1139-1144.
- World Health Organization International Agency for Research on Cancer. IARC Monographs. July 29, 2005.
- Kahlenborn C, Modugno FM et al. Oral contraceptive use as a risk factor for premenopausal breast cancer: a meta-analysis. Mayo Clin Proc. 2006;81:1290-1302.
- Breast Cancer Facts and Figures 2003-2004. American Cancer Society. (www.cancer.org)
- Skegg DCG, Noonan EA, et al. Depot medroxyprogesterone acetate and breast cancer [A pooled analysis of the World Health Organization and New Zealand studies]. JAMA. 1995:799-804.
- Kahlenborn C. Breast Cancer, Its Link to Abortion and the Birth Control Pill. One More Soul, Dayton, 2000.
- Ungchusak, et al. Determinants of HIV infection among female commercial sex workers in northern Thailand: results from a longitudinal study. J Ac Immune Defic Syn Hum Retro. 1996. 12: 500-507.
- Mostad SB, et al. Hormonal contraception, vitamin A deficiency and other risk factors for shedding HIV-1 infected cells from the cervix and the vagina. The Lancet 1997. 350: 922-927 9. Larimore WL, Stanford J. Postfertilization effects of oral contraceptives and their relationship to informed consent. Arch Fam Med.
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- National Cancer Institute. Study of tamoxifen and raloxifene ( STAR) trial. April 26, 2006. (www.cancer.gov/star)
- Ryder RE. Natural Family Planning: Effective birth control supported by the Catholic Church. Br Med J. 1993; 307: 723-726.
Extensive information in the book Love and Fertility, pages: