It has already been published that the administration of a GnRH agonist during the luteal phase could accidentally be involved with the establishment of a pregnancy [11]. Other studies have suggested that GnRH administration at the time of implantation enhances embryo potential by a direct effect on the embryo and improves implantation in oocyte recipients and in normal IVF patients [12, 15].

In a meta-analysis including six relevant RCTs with 2012 patients, it has been shown that GnRH addition during the luteal phase significantly increases the probability of clinical pregnancy and of live birth [8].

It has been classically said that luteal support should continue until the 8th gestation week. However, we have now enough evidence that confirms that luteal support could cease on the day of positive HCG, considering that embryonic HCG will rescue the corpus luteum and will protect the pregnancy. For this reason, we accept that progesterone supplementation can be safely withdrawn at 5 weeks of gestation, and ongoing pregnancy and miscarriage rates will not be affected by this discontinuation [9].

The currently available evidence clearly suggests that luteal phase support is mandatory given that if independently the ovarian stimulation protocol is used, the luteal phase will be altered.