Progestogens in luteal support.

Progestational agents are often prescribed to increase the clinical pregnancy rate in assisted reproduction. Progestogens affect implantation, cytokine balance, natural killer cell activity, arachidonic acid release and myometrial contractility. Progesterone production from the corpus luteum is essential for reproduction, but assisted reproductive technologies (ART) can impair luteal function. ART cycles can be classified into three, fresh cycles in which there may or may not be luteal insufficiency, agonist or antagonist cycles in which there is luteal insufficiency, and luteal support is essential, and donor cycles, in which there is no corpus luteum, and a luteal phase has to be created. However, there is no adequate diagnostic test for luteal insufficiency. This article summarises the effect of various progestogens, progesterone itself whether administered vaginally, intra-muscularly, rectally or subcutaneously, and the effect of the progestogen, dydrogesterone. The time of commencement and cessation of therapy are also discussed. Progestogens are also often used to treat threatened and recurrent miscarriage. In these patients progestogen supplementation may need to be prolonged. In threatened miscarriage, until after all bleeding stops, and in recurrent miscarriage, at least as long as the luteo-placental shift.