Live birth after in vitro maturation and vitrification of immature oocytes retrieved from conventional IVF cycle: a case report

Oocyte cryopreservation is gaining increased recognition as a viable alternative to embryo freezing since this technique satisfied several concerns about ethical, religious and social constraints that are associated with the creation and storage of embryos, and allowed donated oocytes to be used following quarantine in a more cost-effective manner and offered women an ideal modality to not only preserve their fertility but also their reproductive autonomy [1]. Despite this, oocyte cryopreservation is technically challenging and it has been more than two decades since the first successful report of oocyte cryopreservation using the slow-freezing method [2]. Although additional reports of successful oocyte freezing and normal pregnancies followed, the slow-freezing method did not become a routine IVF procedure because of its inefficiency and inconsistency [3]. In contrast, vitrification has been reported more recently as an alternative cryopreservation method that is characterized by simplicity, low cost, and high efficiency for cryopreserving both oocytes and embryos. Oocyte vitrification offers increased success rates in comparison to the slow-freezing method. There are now over 1500 live births resulting from IVF oocyte vitrification reported in the literature [4–6]. In addition, several IVF centers in the world have reported pregnancy rates similar to those of standard fresh IVF treatments [7, 8]. However, very few live births have been reported after cryopreservation of immature oocytes either before in vitro maturation (IVM) [9] or after IVM [10, 11]. The first live birth after slow-freezing of the immature oocytes retrieved from conventional IVF cycles was reported in 1998 [9]. Recently, 4 pregnancies with live birth from immature oocytes retrieved in a natural menstrual cycle, followed by IVM and cryopreservation of the oocytes by vitrification have been reported [10, 11]. However, there has been no report whether the mature oocytes produced by IVM of immature oocytes obtained from conventional IVF cycles can be vitrified and develop into viable embryos. In this case report, we present a pregnancy resulting from transfer of vitrified IVM oocytes generated from immature oocytes of a conventional IVF cycle. To the best of our knowledge, this is the first report of a live birth from vitrification of oocytes produced by IVM of immature oocytes derived from the controlled ovarian hyperstimulation (COH) cycles of a patient in the oocyte donation program.