Luteal-Phase Stimulation

There has been a recent awakening of attention to luteal-phase stimulation (LPS) that could be explained by a combination of circumstances. First, there are physiological grounds to support the notion of this new approach [1–3], provided that it is possible to separate ovarian stimulation and endometrial maturation by stages in order to avoid desynchronisation between embryo and endometrium. Moreover, advances in cryopreservation of oocytes and embryos have made possible an almost total absence of gamete loss after cryopreservation [10, 20]. Also, it is increasingly common in in vitro fertilisation (IVF) to use the antagonist protocol in gonadotropin stimulation and agonist triggering, postponing embryo transfer to a later cycle, not only to avoid the risk of OHS but also with the aim of improving embryo implantation and pregnancy rates [9, 11]. Finally, recent data show that embryos obtained after luteal-phase stimulation may provide optimum pregnancy rates ([13, 14, 17]).