Gonadotrophin-releasing hormone antagonists for assisted conception.

Over the last two decades, a long protocol of Gonadotrophin-releasing hormone agonist (GnRHa) to prevent premature LH surges has been the standard treatment for ovarian stimulation in assisted reproduction. In the long protocols (with GnRHa started either in the mid luteal phase or in the early follicular phase of the preceding cycle) gonadotrophin administration is delayed until pituitary desensitization has been achieved, which usually takes 2-3 weeks. Gonadotrophin-releasing hormone antagonists produce immediate suppression of gonadotrophin secretion, hence, they can be given after starting gonadotrophin administration. This will result in dramatic reduction in the duration of treatment cycle and will avoid estrogen deprivation symptoms associated with GnRH agonist induced down-regulation. Assuming comparable clinical outcome, these benefits would justify a change from the standard long protocol of GnRH agonists to the new GnRH antagonist regimens.