Endometrial structural and inflammatory changes with exogenous progestogens.

Safe and effective contraception is an international public health priority. The long-acting progestogen-only contraceptives are used by over 20 million women worldwide but their main drawback is abnormal uterine bleeding. Such bleeding arises owing to structural and inflammatory changes which compromise endometrial microvascular and epithelial integrity. The molecular and structural changes that lead to the vessel and surface epithelial fragility, and hence the side effect of abnormal uterine bleeding commonly seen with exogenous progestogen use, might be lessened by short-term treatments shown to shorten bleeding episodes.