Ovarian Stimulation Protocol in IVF: An Up-to-Date Review of the Literature

The Assisted Reproductive Technology (ART) was born in order to help couples with infertility issues in having a baby. The first treatments of IVF used the spontaneous cycle of the women, with the retrieval of only one oocyte. Further studies have shown that it is possible to induce ovulation by administrating gonadotropins during the menstrual cycle, in order to obtain a higher number of oocytes. Many stimulation protocols have been introduced for controlled ovarian hyperstimulation of patients undergoing in vitro fertilization treatment. This review describe the different stimulation protocols using follicle-stimulating hormone (FSH) in combination with Gonadotropin releasing hormone (GnRH) either agonist or antagonist, oral supplementations and ovarian triggering. Using GnRH antagonist protocols have been demonstrated to improve significantly the clinical pregnancy rates for expected poor and high-responders, and in those women at high risk of developing ovarian hyperstimulation syndrome (OHSS). Two meta-analyses showed a better outcome in terms of the live birth rate when highly purified human menopausal gonadotropin (HMG) was used for ovarian stimulation compared with recombinant follicle stimulating hormone (rFSH) in the GnRH agonist long protocol. One of the most efficient stimulation protocol is the use of a combined protocol of human derived urinary FSH (uFSH) and rFSH. Combined protocol has resulted in a significant increase in the proportion of mature metaphase II oocytes and grade 1 embryos when compared to either rFSH or uFSH alone. A significantly higher delivery rate was achieved in rFSH+uFSH compared to the other protocols in poor and normal responders. Studying the combination of melatonin with myo-inositol and folic acid has also showed a higher percentage of mature oocytes in the melatonin group and a higher percentage of G1 embryos as well. However, It remains a crucial step to confirm the efficacy of such protocols for clinical application and it is still needs to comparison studies on larger scale with more focused on the differences in patients' response criteria and additional confounding variables, in order to draw more defined conclusions.