[Analysis of influencing factors on pregnancy outcomes after frozen-thawed embryo transfer in patients with infertility and uterine fibroids ≥4 cm in diameter].

Objective

This study aimed to comprehensively investigate influencing factors of pregnancy outcomes after frozen-thawed embryo transfer (FET) in infertile women with intramural fibroids≥4 cm in diameter.

Methods

This was a retrospective case-control study. We retrospectively enrolled 1 551 FET-cycle patients underwent in-vitro fertilisation-embryo transfer (IVF-ET) with at one least intramural fibroid≥4 cm in diameter documented by preoperative transvaginal ultrasonography in the Reproductive Medicine Center of Peking University Third Hospital between January 2020 and December 2024. According to the fertility outcome of FET, patients were divided into the live birth group (n=372) and the non-live birth group (n=1 179). Medical history, baseline clinical characteristics, transvaginal ultrasonographic parameters and IVF laboratory data were compared between the two groups. Multivariate logistic regression was used to identify factors correlated with live birth, and a subgroup analysis was conducted among patients with enlarged uterine volume.

Results

The mean age of the overall patients was (36.6±3.8) years. The live-birth rate per FET cycle was 24.0% (372/1 551), and the full-term birth rate was 86.6% (322/372). Univariate analysis revealed significant differences between two groups in maternal age, serum anti-Müllerian hormone (AMH) level, bilateral antral follicle count (AFC), number of fibroids, uterine length, uterine width, total uterine volume, endometrial thickness on the day of progesterone initiation, and paternal age (all P<0.05). Multivariable logistic regression identified the following independent predictors of failing to achieve a live birth: maternal age>37 years (OR=0.605, 95%CI: 0.470-0.781, P<0.001); uterine volume≥120 cm3 (OR=0.632, 95%CI: 0.470-0.850, P=0.002); and endometrial thickness≤10.6 mm on the day of progesterone initiation (OR=0.630, 95%CI: 0.496-0.799, P<0.001). Subgroup analysis of patients with uterine volume>120 cm3 showed no significant difference in live-birth rates among the four endometrial preparation protocols (down-regulated hormone-replacement, natural cycle, conventional hormone-replacement, and ovulation-induction cycle) after adjustment for potential confounders (P>0.05).

Conclusions

In infertile women undergoing FET with concomitant intramural fibroid≥4 cm, the likelihood of live birth is significantly associated with advancing maternal age, enlarged uterine volume, and reduced endometrial thickness on the day of progesterone initiation. For patients presenting with a uterine volume>120 cm3, the adoption of a down-regulated hormone-replacement protocol fails to confer a demonstrable improvement in live-birth rates.