The results also found that women younger than 55 who had a full-term pregnancy had a slightly higher risk of developing breast cancer during the study. The research was published online on Dec. You likely saw many news reports about this study concluding that giving birth increases breast cancer risk. But the studies were not able to figure out a definitive reason for this short-term increase in risk. The immature breast cells respond to the hormone estrogen as well as hormone-disrupting chemicals in products. Your first full-term pregnancy makes the breast cells fully mature and grow in a more regular way.
The Connection between Pregnancy and Breast Cancer Risk
Breast Cancer Protection From Childbirth Starts Later Than Thought
Why does a first pregnancy after age 35 increase the risk of breast cancer, and what can be done to combat this? Mechanism and preclinical prevention of increased breast cancer risk caused by pregnancy. Image Pregnancy can accelerate the development of precancerous breast cells into cancerous lesions. Breast cancer is the leading cause of cancer deaths in women, killing more than 40, women in the US alone last year American Cancer Society, It is also a highly variable disease, and the significant levels of diversity between different tumours, or within the same tumour, make the diagnosis and treatment of breast cancer a challenge. Pregnancy is one factor that is known to influence the chances of a woman developing breast cancer.
A first pregnancy has 2 effects on breast cancer risk. It increases short-term risk and then it lowers long-term risk. The impact of these risks depends on a woman's age at the time of her first pregnancy [ ]. Women who give birth to their first child at age 35 or younger tend to get a protective benefit from pregnancy [ ].
Women's risk of breast cancer was highest about 5 years after childbirth, and lasted more than 20 years, compared with women who have never given birth, and breastfeeding did not appear to attenuate the risk, a large pooled analysis found. When comparing nulliparous women to parous women, an increased risk of breast cancer peaked at about 5 years after giving birth HR 1. Moreover, this association was not modified by breastfeeding, and varied according to estrogen receptor ER expression, age at first birth, parity, and family history, the authors wrote in the Annals of Internal Medicine. They noted that parity is recognized as a protective factor for breast cancer, but "this may largely apply to the peak ages of incidence after age 60 " and not younger women.