P-668 Progesterone levels on the thawed embryo transfer day in artificial cycles with vaginal progesterone are not a predictor of clinical pregnancy: a prospective study

This is the authors' abstract. We don't add key points for this paper.

Study question Are serum progesterone (P) levels on the thawed embryo transfer day a good predictor of clinical pregnancy with own oocytes in artificial endometrial preparation cycles? Summary answer In artificial endometrial preparation cycles, serum P levels on the thawed embryo transfer day are not a good predictor of clinical pregnancy with own oocytes. What is known already Some studies have shown that low serum P levels on the thawed embryo transfer (ET) day are associated with a lower pregnancy rate after artificial endometrial preparation (AEP) cycles. Other studies have shown that serum P is not a good predictor of pregnancy rates. Furthermore, studies are inconclusive about which cutoff level for P on ET day correlates with better gestational outcomes. Study design, size, duration Prospective cohort study with 235 patients who underwent ET after AEP cycle with estradiol valerate and vaginal micronized P (200 mg/ 8 h). All patients underwent blastocyst-stage or cleavage-stage ET with embryos from their own oocytes, without preimplantation genetic testing for aneuploidies, after AEP cycle, with a triple layer endometrium > 7 mm. The study was carried out at the Human Reproduction Center of Ribeirão Preto Clinical Hospital from November 2021 to June 2023. Participants/materials, setting, methods Blood was collected between 8–10 am on the thawed ET day and serum P concentration was measured. The primary outcome was clinical pregnancy (CP) beyond pregnancy week 8. A ROC curve detected the best P cutoff level that correlated with higher CP rate. Thereafter, patients were categorized into those with serum P above and below the cutoff level. Multivariate logistic regression was performed to verify which variables were predictors of CP and P levels. Main results and the role of chance Serum P measured on the ET day showed no significant difference between patients who had CP and those who did not (12.76 +4.1 versus 11.9 + 5.6, p 0.3318). The cutoff level for serum P measured on the ET day above which correlates with higher CP rate was 10.6 ng/mL (AUC 0.58), with a sensibility of 72% and specificity of 44%. Patients who had serum P on the day of ET above this value had a significantly higher CP rate than those who had it below this value (25.9% versus 14.6%) (p 0.0372). However, when the multivariate logistic regression model was performed, there was no significant difference in the CP between the groups (OR 2, 95%IC: 0.9-5). Predictors of CP in the study were the presence of at least one top-quality embryo transferred (OR 2.6, 95%IC: 1-6.6) and the transfer of embryo at the blastocyst-stage (OR 5.2, 95%IC: 1.9-14). The presence of endometriosis was negatively associated with CP (OR 0.2, 95%IC: 0.09-0.9). Limitations, reasons for caution The small sample size is a limitation. We included the blastocyst-stage and the cleavage-stage embryo transfer. Only women with vaginal micronized P were included. Extrapolation to other P administration forms needs to be evaluated. Wider implications of the findings Monitoring serum P levels on the day of ET in AEP cycles with vaginal micronized P is not justified as serum P levels are not a good predictor of CP in cycles with own oocytes. Trial registration number Not applicable