P-499 Individualization of the mean luteal phase after frozen embryo transfer with hormone replacement therapy
Authors: Grau S , Julve R , Aurell R , Barbed C , Rocafort E 
Published: June 2023

Abstract

Study question
Objective: To determine in embryo cryotransfer cycles with hormone replacement therapy whether progesterone levels five days after transfer &lt; 15.7 ng/mL correlate with reproductive outcomes.

Summary answer
Conclusion: We cannot affirm that low levels of progesterone in the mid luteal phase after cryotransfer are an independent factor of evolutionary gestation.

What is known already
n the transfer of frozen embryos with hormone replacement therapy after a period of endometrial preparation with estrogens for 10-12 days, luteal phase support with vaginal progesterone is administered as many days as the embryo to be transferred, as reported by Van de Vijver et al 2001. After reporting that low progesterone levels on the day of transfer were associated with worse outcomes, our purpose is to evaluate progesterone levels after transfer with the first prospective study monitoring post-transfer progesterone levels to see if its supplementation correlates with better reproductive outcomes.

Study design, size, duration
Study desing: Analytical, observational, longitudinal, prospective study conducted at the Assisted Reproduction Unit of Hospital Quironsalud Barcelona between December 2021 and May 2022. 159 patients aged 18-42 years who have undergone a cycle of frozen embryo transfer (CT) of their own or donated embryos with hormone replacement therapy.

Participants/materials, setting, methods
Material and methods: Determine in embryo cryotransfer cycles with hormone replacement therapy with estradiol, luteal phase support of micronized natural progesterone five full days prior to the transfer of a blastocyst.Determination of progesterone levels five days after transfer, if levels &gt; = 15.7ng (group C) we followed the same guideline, if &lt; 15.7 ng one group was supplemented with 25 mg Psc (group A), and another group of patients (group B) was not supplemented.

Main results and the role of chance
Results: Total of 159 patients with mean age of 37.86 years, mean antimuleriana value 2.95 ng/ml, antral follicle count of 11.54 and mean endometrial thickness of 8.93mm. 55.97%(n = 89) TC had P4D+10 &lt;15.7ng. Pregnancy rate (BHCG&gt;5mIUI/mL) was higher in the group with progesterone 5 days after transfer ( P4D+10) &gt; =15.7ng with 65.71% CI95%[53.31,76.38] p = 0.65, and in the group of P4D+10 &lt; 15.7 ng became pregnant 53.57% CI95%[34. 21,71.99] p = 0.53 of group A with respect to 45.90% IC95%[33.26,59.06] p = 0.45 group B. Clinical evolutionary pregnancy rate was higher in group A 80% vs 67.86% of group B, p-value=0.06. Abortion rate lower in group A 20% vs 32.14% group B, p = 0.01.

Limitations, reasons for caution
Limitations. There are few previous studies that allow us to support our arguments, the variability of progesterone levels in blood throughout the day can alter the results,nevertheless, and the sample size is small and it is difficult to find significant differences.

Wider implications of the findings
We did observe that &gt;50% (55.97%) of the patients presented low values of progesterone after the embryo frozen transfer, with an improvement in pregnancy rate 53.57% vs 45.90% when these were rescued with subcutaneous progesterone. About 7% of pregnancies would be lost without this monitoring and supplementation.

Trial registration number
not applicable