Short-term oral progesterone administration antagonizes the effect of transdermal estradiol on endothelium-dependent vasodilation in young healthy women

This study examined the effects of short-term oral micronized progesterone on the vascular benefits of transdermal estradiol in 17 premenopausal women. Participants underwent hormone suppression with a gonadotropin-releasing hormone antagonist for 10-12 days, followed by supplementation with either 200 mg oral micronized progesterone or 0.1 mg transdermal estradiol. The results