There is already significant evidence that progesterone (unlike synthetic progestins) has no adverse effects on cardiovascular risk factors.
No change in any of the thrombotic or inflammatory markers studied was observed, despite significant symptomatic improvement compared to placebo, in 30 women receiving 20 mg/day progesterone cream for 4 weeks (Stephenson et al. 2004).
When bioidentical progesterone (an oral micronized preparation) was used in one group in the PEPI study in place of medroxyprogesterone acetate (MPA), this group had a significantly higher HDL cholesterol levels than the MPA group, indicating a different pharmacological effect than the synthetic progestin with a more favorable effect on blood lipids (Writing Group for the PEPI Trial, 1995).
Not only is there a lack of adverse effects of bioidentical progesterone on the cardiovascular system, but there is evidence of beneficial effects also. A progesterone vaginal gel produced an increase in exercise tolerance in postmenopausal women with coronary artery disease or previous myocardial infarction who were being treated with estradiol, while MPA did not, compared with estradiol alone (Rosano et al. 2000), suggesting an advantage for progesterone in women at risk for cardiovascular disease.
Progesterone’s long term hemostatic role is suggested by its ability to reduce coronary hyperreactivity even in the presence of atherosclerosis in oophorectomized rhesus monkeys (Hermsmeyer et al. 2004). Koh et al. (2004) reported that progesterone together with lower dose conjugated equine estrogens (CEE) had comparable beneficial effects to conventional high dose CEE on flow mediated dilation, high density lipoproteins, and triglycerides, which may suggest that peripheral vascular function in postmenopausal women is markedly improved by direct actions on the vascular wall.
The reduction of the risk of heart attacks, angina pectoris, stroke, and other major heart and vascular disease by restoring hormone balance could delay the decline in cardiovascular function in women for decades.
With thanks to http://www.womeninbalance.org