Background
OHSS, OI, PCOS, infertility, impaired ovulation, ovarian hyper stimulation syndrome
POLYCYSTIC OVARY SYNDROME, COMPLICATIONS
Polycystic ovary syndrome (PCOS) that associated with impaired ovulation is one of the most common causes of infertility with a prevalence rate of 75%. Ovulation induction (OI) is considered one of first options infertility management in women with PCOS history. Due to different causes such as resistance to treatment, failure of OI, assisted reproductive treatment (ART) placed an alternative treatment for these patients. Diversity of ovarian stimulation (OS) protocols for in-vitro-fertilization (IVF), concerns about the risk of ovarian hyper stimulation syndrome (OHSS), higher serum estradiol level, faster endometrial maturation, and such approaches as freeze-all embryos policies are challenges facing IVF in patients with PCOS [Adoption of an optimal OS protocol in these patients to overcome these challenges is highly important. Based on the available scientific evidence, patients with PCOS in the IVF cycle are recommended to undergo OS protocol with gonadotropin-releasing hormone antagonists (GnRH) antagonists. This protocol is preferred over the OS protocol with GnRH-agonist due to reduced OS duration, dose of gonadotropin, and the occurrence of OHSS [In other hand, choosing proper medications can be an important tool to achieve a desired OS outcome and reduce associated complications, such as OHSS. In this regard, the mild ovarian stimulation (mild-OS) and minimal ovarian stimulation (minimal-OS) protocols are cost-effective alternatives [Mild-OS refers to a protocol, which decreases the dose or duration gonadotropin administration in comparison with common protocols in the single OS cycle with GnRH-antagonists [Minimal-OS refers to a protocol, which aims to achieve a maximum of five oocytes. According to the International Society for Mild Approaches in Assisted Reproduction (ISMAAR), minimal-OS aims to obtain 2–7 oocyte. Minimal-OS is performed by administrating anti-estrogenic factors (such as clomiphene citrate (CC)) or aromatase inhibitors (such as letrozole) alone or in combination with a small dose of gonadotropin [In addition to the OS and medication protocols, the type of gonadotropin, urinary or recombinant, used for OS influences the IVF cycle outcome. Different types of gonadotropin can be synthesized through purifying human urine such as urinary human menopausal gonadotropin (u-HMG), highly purified HMG (HP-HMG) and recombinant follicle stimulating hormone (r-FSH) [According to evidence, there is an agreement only in using GnRH-antagonists to OS in patients with PCOS; whereas, there is no agreement on the optimal medication and gonadotropin administration for OS to achieve the best fertility outcome in these patients. Randomized control trials (RCTs) on mild/minimal OS protocols in women with PCOS history are scant. The present study aimed to investigate both the effectiveness of minimal-OS, as compared to mild-OS, among PCOS patients and the effect of gonadotropin types in OS cycles with GnRH-antagonist.