OBJECTIVE To assess the impact of withholding doxycycline on the success rate of natural cycle frozen embryo transfers (NC-FET). DESIGN Retrospective cohort study. SETTING Single academic institution. PATIENT(S) Women undergoing 250 NC-FET with euploid blastocysts performed by a single provider. INTERVENTION(S) One hundred and twenty-five NC-FET cycles performed after January 2019 without antibiotic administration compared with 125 NC-FET cycles before January 2019 with doxycycline administration. MAIN OUTCOME MEASURE(S) Primary outcome: live birth (LB) or ongoing pregnancy rate (OPR, defined as pregnancies ≥13 weeks); secondary outcomes included positive β-human chorionic gonadotropin (β-hCG) level and clinical pregnancy rate (CPR, defined as the presence of fetal cardiac activity on ultrasound). RESULT(S) Each group of women comprised 125 NC-FET during the study period of March 2017 to March 2020. The women's mean age was 36.3 years and mean body mass index was 24 kg/m2. Between the two groups, the baseline characteristics were similar, including age, body mass index, race, smoking status, parity, endometrial thickness, Society of Assisted Reproductive Technology diagnosis, and number of prior failed transfers. Comparing NC-FET with doxycycline administration versus without, we found no statistically significant difference in LB-OPR (64% vs. 62.6%), positive β-hCG (72.8% vs. 74.0%), or CPR (68% vs. 65.9%). After controlling for all variables in a logistic regression, doxycycline still had no effect on LB-OPR. CONCLUSION(S) In this analysis of similar patients undergoing NC-FET by a single provider, withholding doxycycline does not reduce success rates. Given the risks of antibiotics, our findings support withholding their use in NC-FET.

中文翻译：

---

停用抗生素不会降低自然周期冷冻胚胎移植的临床妊娠结局

目的 评估停用强力霉素对自然周期冷冻胚胎移植 (NC-FET) 成功率的影响。设计 回顾性队列研究。设置 单一学术机构。PATIENT(S) 接受 250 NC-FET 并由单一提供者进行整倍体囊胚的女性。干预措施 2019 年 1 月之后未使用抗生素的情况下进行了 125 个 NC-FET 周期，而 2019 年 1 月之前使用强力霉素进行了 125 个 NC-FET 周期。主要结局指标 主要结局指标：活产 (LB) 或持续妊娠率 (OPR，定义为妊娠 13 周以上)；次要结果包括阳性 β-人绒毛膜促性腺激素 (β-hCG) 水平和临床妊娠率 (CPR，定义为超声显示胎儿心脏活动的存在)。结果 在 2017 年 3 月至 2020 年 3 月的研究期间，每组女性包括 125 NC-FET。女性的平均年龄为 36.3 岁，平均体重指数为 24 kg/m2。两组之间的基线特征相似，包括年龄、体重指数、种族、吸烟状况、产次、子宫内膜厚度、辅助生殖技术协会的诊断以及先前失败的移植次数。将 NC-FET 与多西环素给药与未给药进行比较，我们发现 LB-OPR（64% 与 62.6%）、阳性 β-hCG（72.8% 与 74.0%）或 CPR（68% 与 65.9）没有统计学显着差异%）。在逻辑回归中控制所有变量后，强力霉素仍然对 LB-OPR 没有影响。结论（S）在对由单一提供者进行 NC-FET 的类似患者的分析中，扣留多西环素不会降低成功率。鉴于抗生素的风险，我们的研究结果支持在 NC-FET 中停止使用它们。