Comparison of the predictive value of progesterone-related indicators for pregnancy outcomes of women undergoing the short-acting GnRH agonist long protocol: a retrospective study

Background: There are many progesterone (P) elevation-related indicators for predicting pregnancy outcomes, including the serum P, P-to-oestradiol ratio (P/E-2), P-to-follicle index (PFI), and P-to-mature oocyte index (PMOI); however, due to inconsistencies in study populations and controlled ovarian hyperstimulation (COH) protocols among studies, these indicators are controversial. Moreover, no researchers have included these four commonly used indicators in one study to compare their predictive efficacies. The objective of this study was to compare the predictive value of P-related indicators for pregnancy outcomes of women undergoing the short-acting GnRH agonist long protocol. Methods: A total of 612 infertile women undergoing IVF/ICSI were recruited for this study. Serum samples were obtained on the morning of HCG injection for serum P and E-2 measurements. Transvaginal ultrasound was performed to determine the follicle count (>= 14 mm in diameter). The number of mature oocytes was observed in the embryo laboratory after oocyte retrieval. Results: In cases of P < 2.5 ng/ml, there was no significant difference in the serum P level or P/E-2 between the pregnant group and the non-pregnant group. The PFI and PMOI of the pregnant group were significantly lower than those of the non-pregnant group. According to the stratified analysis of the ovarian response, only the PMI and PMOI of the pregnant women in the normal ovarian response group were lower than those of the non-pregnant women. To compare the predictive value of the PFI and PMOI in IVF/ICSI outcomes, the patients were divided into four groups. The good-quality embryo rate and clinical pregnancy rate were highest in Group A (low PFI and low PMOI) and lowest in Group D (high PFI and high PMOI). In the two groups with discordant PFI and PMOI, namely Group B (low PFI and high PMOI) and Group C (high PFI and low PMOI), the good-quality embryo rate and clinical pregnancy rate were not significantly different. Conclusions: The PFI and PMOI had equal value in predicting clinical pregnancy outcomes in the normal ovarian response group undergoing the short-acting GnRH agonist long protocol. Each clinical centre can choose one of the indicators according to their actual situation in clinical practice and establish individual cut-off values for PFI and PMOI based on their own hormonal measurements.