P-667 The attenuated response to elevated serum progesterone levels on pregnancy outcomes of fresh IVF/ICSI cycles in older patients
Authors: Fung K K , Ip N P P , Chung P W J , Chan Y L D 
Published: June 2023

Abstract

Study question
Whether there are different impacts of serum progesterone (P) levels on the day of trigger on pregnancy outcomes in patients of different age groups.

Summary answer
Our results suggest that the pregnancy outcome was less sensitive to progesterone elevation in older patients.

What is known already
It is now generally believed that the P elevation at the late follicular phase reduces the pregnancy rate by opening the implantation window prematurely and disrupt the embryo-endometrial synchrony. Previous studies further investigated the effect of developmental stages of embryo, number of oocytes retrieved, cause of infertility and different stimulation regimens on the association of P level and the likelihood of pregnancy. However, the study of maternal age on such association is scarce. A previous study found that LH receptor (LHCGR) and progesterone receptor (PGR) were up regulated in advanced age group.

Study design, size, duration
This was a non-interventional, retrospective cohort study of patients undergoing routine practice in a university-based fertility center between 2015 and 2021. One thousand five hundred and seventeen IVF/ICSI cycles among 1305 patients were included in the analysis.

Participants/materials, setting, methods
Fresh ET using autologous oocytes with serum P level measured on the day of hCG administration were included. Exclusion criteria include cycles without P measurement, using frozen oocytes, PGT cycles, freeze-all cycles, oocyte donation and no embryo transfer cycles. The patient age was divided into 3 groups: group 1 included patients at age 35 or below, group 2 included patients at age 36 to 39, group 3 included those at 40 years old or above.

Main results and the role of chance
We performed logistic regression analysis for each group to determine the contributing factors to the live birth outcome. In group 1, age, serum P level, number of usable embryos, embryo grading and endometrial thickness were found to be significantly associated with live birth. In group 2, age and number of usable embryos were significantly associated with live birth. However, total dose of gonadotropin was found to be the sole contributing factor to live birth in group 3. We also divided the P levels into low (≤0.50 ng/mL), median (0.51-1.00 ng/mL) and high (&gt;1.00 ng/mL) and compared the live birth rate in each age groups. The live birth rate was found to be significantly reduced with increasing P levels (40.3% vs. 35.5% vs. 23.6%, p = 0.005). No significant difference in live birth rate between different P levels was found in age group 2 and 3.

Limitations, reasons for caution
The limitation of the study is its retrospective nature which may have led to bias in the interpretation of the data. There were also significantly higher proportion of cleavage-stage embryo to blastocyst transfer in the older group.

Wider implications of the findings
The negative association of premature progesterone rise at pre-ovulatory phase to the IVF fresh ET outcome was more prominent for younger patients. This may be one of the contributing factors that accounts for the great heterogeneity in the cut-off of P and its predicting power in different studies.

Trial registration number
Not applicable