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effects_of_pregnancy_on_breast_cancer_risks [2015/10/23 07:35]
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effects_of_pregnancy_on_breast_cancer_risks [2017/05/30 09:58] (current)
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 Early and a repeated number of pregnancies provide protective benefits against breast cancer. During the first half of pregnancy, the proliferation phase, Type 1 and Type 2 lobules increase in number. During the second half of pregnancy (after week 20), cancer-vulnerable Type 1 and Type 2 lobules begin to mature into cancer-resistant Type 4 lobules. After 32 weeks of pregnancy, sufficient Type 4 lobules have developed that a mother is protected against breast cancer, and she incrementally gains the breast cancer risk reduction that will maximize at 40 weeks. After birth and after a mother has lactated and [[effects_of_breastfeeding_on_breast_cancer|breastfed]] (or should she choose not to breastfeed),​ Type 4 lobules regress to Type 3 lobules, which retain the epigenetic changes that protect against cancer’s development. Early and a repeated number of pregnancies provide protective benefits against breast cancer. During the first half of pregnancy, the proliferation phase, Type 1 and Type 2 lobules increase in number. During the second half of pregnancy (after week 20), cancer-vulnerable Type 1 and Type 2 lobules begin to mature into cancer-resistant Type 4 lobules. After 32 weeks of pregnancy, sufficient Type 4 lobules have developed that a mother is protected against breast cancer, and she incrementally gains the breast cancer risk reduction that will maximize at 40 weeks. After birth and after a mother has lactated and [[effects_of_breastfeeding_on_breast_cancer|breastfed]] (or should she choose not to breastfeed),​ Type 4 lobules regress to Type 3 lobules, which retain the epigenetic changes that protect against cancer’s development.
  
-A woman who has her first full-term pregnancy at age 20 has a 90 percent lower risk of breast cancer than a woman who remains childless or waits until she is 30 for her first full-term pregnancy.((Mats Lambe, “Chapter Six: Reproductive Factors,” in //Breast Cancer Epidemiology//,​ ed. Christopher I. Li (New York: Springer, 2009), 129-136.)) With each pregnancy after her first, a mother reduces her risk of breast cancer by 10 percent.((Mats Lambe, Chung-cheng Hsieh, Hsiao-wei Chan, Anders Ekbom, Dimitrios Trichopoulos,​ and Hans-Olov Adami, “Parity, Age at First and Last Birth, and Risk of Breast Cancer: A Population-Based Study in Sweden,” //Breast Cancer Research and Treatment// 38 (1996): 305-311.)) Each year a woman delays pregnancy after age 20, her risk of premenopausal breast cancer increases 5 percent and her risk of postmenopausal breast cancer increases 3 percent.((Françoise Clavel-Chapelon and Mariette Gerber, “Reproductive Factors and Breast Cancer Risk,” //Breast Cancer Research and Treatment// 72, no. 2 (2002): 107-115.)) This results from the lengthening of the “susceptibility window,” the period between menarche and a first full-term pregnancy, when the breast is composed solely of cancer-vulnerable Type 1 and Type 2 lobules and is most susceptible to carcinogenesis (the formation of normal cells into cancer cells). A woman’s breast cancer risk increases 0.7 percent for each year subsequent births are delayed after the first time she gives birth.((Adriano Decarli, Carlo La Vecchia, Eva Negri, and Silvia Franceschi, “Age at Any Birth and Breast Cancer in Italy,” //​International Journal of Cancer// 67, no. 2 (July 1996): 187-189.+A woman who has her first full-term pregnancy at age 20 has a 90 percent lower risk of breast cancer than a woman who remains childless or waits until she is 30 for her first full-term pregnancy.((Mats Lambe, “Chapter Six: Reproductive Factors,” in //Breast Cancer Epidemiology//,​ ed. Christopher I. Li (New York: Springer, 2009), 129-136.)) With each pregnancy after her first, a mother reduces her risk of breast cancer by 10 percent.((Mats Lambe, Chung-cheng Hsieh, Hsiao-wei Chan, Anders Ekbom, Dimitrios Trichopoulos,​ and Hans-Olov Adami, “Parity, Age at First and Last Birth, and Risk of Breast Cancer: A Population-Based Study in Sweden,” //Breast Cancer Research and Treatment// 38(1996): 305-311.)) Each year a woman delays pregnancy after age 20, her risk of premenopausal breast cancer increases 5 percent and her risk of postmenopausal breast cancer increases 3 percent.((Françoise Clavel-Chapelon and Mariette Gerber, “Reproductive Factors and Breast Cancer Risk,” //Breast Cancer Research and Treatment// 72, no. 2 (2002): 107-115.)) This results from the lengthening of the “susceptibility window,” the period between menarche and a first full-term pregnancy, when the breast is composed solely of cancer-vulnerable Type 1 and Type 2 lobules and is most susceptible to carcinogenesis (the formation of normal cells into cancer cells). A woman’s breast cancer risk increases 0.7 percent for each year subsequent births are delayed after the first time she gives birth.((Adriano Decarli, Carlo La Vecchia, Eva Negri, and Silvia Franceschi, “Age at Any Birth and Breast Cancer in Italy,” //​International Journal of Cancer// 67, no. 2 (July 1996): 187-189.
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-This entry draws heavily from [[http://​marri.us/​abortion-breast-cancer|Induced Abortion and Breast Cancer]].))+This entry draws heavily from [[http://​marri.us/​research/​research-papers/​induced-abortion-and-breast-cancer/|Induced Abortion and Breast Cancer]].))