This article was released by The North American Menopausal Society in 2011. It is entitled “VTE and HRT”. It looks at the mode of administration of estrogen. It found that estrogen administered orally; that went to the liver before the blood, triggered a phenomenon called the “coagulation cascade”. This phenomenon may have been responsible for the clots that led to the heart attacks and strokes experienced in the Women’s Health Initiative, (WHI). It reports that estrogen administered in a manner that goes to the blood before the liver (transdermal – which would also apply to subcutaneous) did not trigger the coagulation cascade. Interesting reading (a bit technical) that may help to answer questions you may have about possible cardiovascular risks and estrogen therapy. PDF