Effect of Flexible GnRH antagonist and long GnRH agonist protocols on follicular fluid levels of PlGF, AMH, oocyte’s morphology, and other IVF/ICSI outcomes in normo-ovulatory women
Authors: Kadoura Sally , Alhalabi Marwan , Nattouf Abdul Hakim 
Published: March 2022

Background
Gonadotropin-releasing hormone (GnRH) analogues are commonly used to prevent premature luteinizing hormone (LH) surge during In-Vitro Fertilization/ Intra-Cytoplasmic Sperm Injection (IVF/ICSI) cycles in routine practice. However, it is still unclear whether they have different effects on the follicular microenvironment in normo-ovulatory women.
Settings:
This study was performed at Orient Hospital, Damascus, Syrian Arab Republic, from December 2019 to August 2021.
Methods
In this interventional, prospective, parallel, non-randomized, open-label controlled clinical trial, a total of 83 normo-ovulatory women were allocated to take either the long GnRH agonist protocol (n = 50) or the flexible GnRH antagonist protocol (n = 33). The trial was originally designed to be a randomized control trial. However, due to a lack in the drug supply during a certain point of the study duration, we used a non-random study design. Follicular fluid (FF) samples were collected on the retrieval day, and the FF levels of Placental growth factor (PlGF) and Anti-Müllerian hormone (AMH) were measured using ELISA Kits. Before being subjected to ICSI, the mature oocytes from both groups were morphologically assessed under an inverted microscope at 400x magnification. In addition, the embryological and clinical IVF/ICSI outcomes were detected.
Results
The two groups did not differ significantly in any of the baseline characteristics. The FF PlGF levels were significantly lower, while FFAMH levels were insignificantly higher in the GnRH antagonist group (FF PlGF; GnRH agonist = 140.46 ± 42.46 pg/ml vs. GnRH antagonist = 120.49 ± 35.07 pg/ml; P value = 0.029). (FF AMH; GnRH agonist = 7.40 ± 5.69 ng/ml vs. GnRH antagonist = 8.51 ± 7.93 ng/ml; P value = 0.440). The stimulation duration was significantly shorter in the GnRH antagonist group compared to the long-agonist one (GnRH agonist = 8.28 ± 1.09 days vs. GnRH antagonist = 7.26 ± 0.89 days; P value < 0.001). On the other hand, although the consumed dose of gonadotropin was lower in the antagonist group, the difference between the two groups was not statistically significant (GnRH agonist = 2523.00 ± 1034.11 IUs vs. GnRH antagonist = 2468.18 ± 879.53 IUs; P value = 0.952). However, there were not any significant differences between the two groups in embryological or clinical IVF/ICSI outcomes except for the endometrial thickness, which was thinner in the GnRH antagonist group, and the result almost reached significance level (GnRH agonist = 9.66 ± 1.39 mm vs. GnRH antagonist = 9.03 ± 1.51 mm; P value = 0.058). In addition, the morphological assessment of MII oocytes showed comparable oocytes morphology in both groups.
Conclusions
Flexible GnRH antagonist protocol and the long GnRH agonist protocol regulate the follicular microenvironment and angiogenesis differently in normo-ovulatory women. However, these differences have no influence on the oocyte’s morphology or the IVF/ICSI outcomes. In addition, although both protocols provide acceptable endometrial thickness, caution should be taken when designing the plans therapy for cases that are considered high risk of developing thin endometrial when stimulated with the flexible GnRH antagonist protocol.
Study registration:
This trial was prospectively registered at clinicaltrials.gov site under registration number (NCT04724343).