Background: Recent studies have suggested a potential correlation between having a caesarean section scar defect (CSD) and reduced success rates in frozen embryo transfer (FET) cycles after in vitro fertilisation (IVF). However, comprehensive data on this association remain limited. Aim: To investigate the influence of different endometrial preparation protocols in women with CSD undergoing FET. Methods: This retrospective cohort study enrolled women between March 2020 and February 2023 at two hospitals in Vietnam. Participants were aged 18–42 years, had regular menstruation, had undergone <3 previous IVF cycles, and underwent FET with artificial cycle (AC) or natural cycle (NC)/modified NC endometrial preparation. The primary outcome was the live birth rate after the first FET following CSD diagnosis. Results: We studied 130 patients (98 in the AC group and 32 in the NC group). The live birth rate did not differ significantly between the AC and NC groups (22.4% vs. 21.9%; RR 1.03, 95% confidence interval CI 0.48–2.17; Formula: see textFormula: see text 0.965), but the positive Formula: see text-human chorionic gonadotropin (hCG) rate was significantly higher in the AC group (46.9% vs. 25%, relative risk (RR) 1.88, 95% confidence interval CI 1.09–4.25; Formula: see textFormula: see text 0.03). The miscarriage rate at <24 weeks was substantially higher in the AC group (14.3%) than in the NC group (3.12%) (RR 4.57, 95% CI 0.63–33.41; Formula: see textFormula: see text0.083). Conclusion: Endometrial preparation method may not affect the live birth rate in women with CSD undergoing FET. Differences in positive pregnancy tests and clinical pregnancies might indicate a benefit for the AC group. However, as miscarriage occurred less with NC, clinicians should consider the miscarriage rate when choosing the AC protocol in this setting.
Tran et al. (Sun,) studied this question.
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