Why would a woman who has an induced abortion before her firstborn child suffer an increased risk of breast cancer?
A woman's breast is especially sensitive to carcinogenic (i.e., cancer producing) influence before she delivers her first child. When a woman becomes pregnant, a number of hormone levels increase dramatically in her body. Three especially notable ones are estradiol, progesterone (i.e., the female sexual hormones), and B-hCG (Beta-human Chorionic Gonadotropin). All of these hormones, especially the latter, serve to stimulate immature breast cells to mature into fully differentiated cells [145A]. If this process gets artificially interrupted, by way of an induced abortion, the hormone levels drop dramatically thereby suspending the natural process of maturation of many of the woman's breast cells. This is referred to as a "hormonal blow" by researchers. These cells are now "vulnerable" to carcinogens since they were left "in limbo": that is, they started the maturation process, but were never able to complete it. [Cells that have fully matured are less vulnerable to carcinogens than cells that are in the process of maturation].