P-643 Menopause should not be considered a confounding factor in endometrial preparation protocol’s comparative clinical trials: a retrospective cohort study with 1.109 euploid single embryo transfers
Authors: Walker V , Garcia-Faura A , Diaz M , Zabala P , Botia S , Garcia F , Montalvo V , Marques B 
Published: July 2024

Abstract

Study question
Does menopause have an impact on obstetric and perinatal outcomes when performing elective euploid single-blastocyst transfers (eeSBT) in a hormonal replacement treatment (HRT) protocol?

Summary answer
eeSBT in a non-menopause elective HRT group(eHRT) did not show higher success rates nor better obstetric and perinatal outcomes compared to a menopause HRT group(mHRT).

What is known already
Menopause has been suggested to be a confounding factor in clinical trials when comparing the results and success rates for endometrial preparation in modified natural cycle (mNC) Vs HRT: including menopause patients could lead to selection bias seen that they can never be included in the mNC group. Few data are available on eeSBT ≥3BB (Gardner score) cryotransfers comparing obstetric and perinatal results between eHRT and mHRT, to have the opportunity to include them all in further comparative trials, with a low bias risk.

Study design, size, duration
Retrospective single-centre comparative study, including 1.109 eeSBT (≥3BB, Gardner score) between Jan-2018 and Dec-2022: 1.025 (92,4%) in eHRT and 84 (7,6%) in mHRT.
The eHRT and mHRT groups were homogeneous for egg donor’s age (29,1±5,9 yo Vs 25,8±4,1 yo) recipient’s age (41,4±4,9 yo Vs 44,9±4,7 yo), body mass index (22,6±4,7 Vs 22,6±5,3) severe male factor (3,5% Vs 3,6%), the need for sperm donation (30,0% Vs 35,7%), and the average throphoectoderm embryo quality (A = 32,5% Vs A = 29,8%).

Participants/materials, setting, methods
We studied the clinical, obstetric and perinatal outcomes of the 1.109 eeSBT, comparing eHRT and mHRT groups for: pregnancy rate, miscarriage rate, live birth rate, twin pregnancy rate, severe preeclampsia, preterm birth rate (&lt;37, &lt;35, &lt;32 and &lt;28 weeks) and neonatal weight. We used Chi-square test and T-Test to compare groups (p &lt; 0,05).

Main results and the role of chance
There were no statistically significant differences between eHRT and mHRT groups when comparing pregnancy rates (63,7% Vs 64,3%, p = 0,92), miscarriage rates (15,6% Vs 11,1%, p = 0,053) and live birth rates (44,3% Vs 48,8%, p = 0,42); no significant differences were found in the severe preeclampsia rate(2,0 Vs 1,2, p = 0,84), nor in the twin pregnancy rate (0,9 Vs 2,4, p = 0,34) even if it almost tripled in the mHRT group.
Preterm, major and extreme preterm birth rates were comprable between eHRT and mHRT groups: &lt;37 weeks (9,9% Vs 4,9%, p = 0,29) &lt; 35 weeks (3,3% Vs 0, p = 0,23) &lt;32 weeks (1,3% Vs 0, p = 0,46) &lt;28 weeks (0,2% Vs 0, p = 0,76). There were no significant differences in neonatal weight (3292 + 481g Vs 3.135 + 419g, p = 0,052).

Limitations, reasons for caution
In a preliminary study, we compared and additional 245 eeSBT in mNC with the HRT group, and no significant differences in obstetric or perinatal outcomes were reported when including or excluding the mHRT sub-group.

Wider implications of the findings
In eeSBT, the eHRT group did not report better obstetric nor perinatal results compared to the mHRT group; further prospective clinical trials comparing mNC Vs HRT should not consider menopause as a major confouding factor, when using eeSBT.

Trial registration number
Not Applicable