“…During the luteal phase, the corpus luteum produces progesterone, which prepares the estrogen-primed endometrium for embryo implantation ( Heine et al ., 2017 ). Progesterone is known to be an essential hormone required for successful implantation and continuation of early pregnancy by inducing sequential events in the endometrium during the luteal phase, including maturation, secretory transformation of the glandular elements, edema formation, vascular proliferation and stroma decidualization ( Heine et al ., 2017 ; Ho et al ., 2008 ; Satir et al ., 2013 ; Beltsos et al ., 2014 ). In assisted reproductive technology (ART) treatment, the down regulation of luteinizing hormone (LH) secretion by the use of gonadotropin-releasing hormone (GnRH) agonists or antagonists, can lead to luteal phase disruption as the amount of progesterone produced is not sufficient; this can lead to ineffective development of the endometrium, hence reduction in the implantation rate ( Heine et al ., 2017 ; Ho et al ., 2008 ; Satir et al ., 2013 ; Beltsos et al ., 2014 ; Bahceci & Ulug, 2008 ).…”