OBJECTIVE To study the effect of frozen embryo transfer (FET) preparation protocol on incidence of subchorionic hematoma (SCH) and serum hormone levels. DESIGN Retrospective cohort study. SETTING University-affiliated fertility center. PATIENT(S) Patients who underwent FET at the New York University Langone Fertility Center. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) The primary outcome was incidence of SCH by protocol in FET cycles. RESULT(S) There were 1,273 FET cycles that met criteria for inclusion. The frequency of SCH was lower in natural compared with programmed cycles (P<.05; relative risk = 0.4 [0.27-0.78]; odds ratio = 0.4 [0.23-0.75]). Serum estrogen level was higher in programmed compared with natural cycles on day of progesterone initiation (P<.001) and cycle day 28 (P<.001). However, serum estrogen levels at the same time points were not associated with formation of SCH in programmed or natural cycles. CONCLUSION(S) This is the first study to evaluate the formation of SCHs by FET protocol type. Our results highlight that high serum estradiol levels do not independently lead to an increase in rate of SCH. Further research must be done to understand other clinical, or perhaps molecular, differences between natural and programmed FET cycle preparations that can be better associated with SCH formation.

中文翻译：

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药物或天然单整倍体冷冻胚胎移植周期中绒毛膜下血肿的比较

目的研究冷冻胚胎移植（FET）制备方案对绒毛膜下血肿（SCH）发生率和血清激素水平的影响。设计 回顾性队列研究。设置 大学附属生育中心。患者 在纽约大学朗格尼生育中心接受 FET 治疗的患者。干预措施 无。主要结果测量 主要结果是 FET 周期中协议规定的 SCH 发生率。结果 有 1,273 个 FET 周期符合纳入标准。与程序周期相比，自然 SCH 的频率较低（P<.05；相对风险 = 0.4 [0.27-0.78]；优势比 = 0.4 [0.23-0.75]）。与孕激素起始日 (P<.001) 和周期第 28 天 (P<0.001) 的自然周期相比，程序化的血清雌激素水平更高。然而，同一时间点的血清雌激素水平与程序化或自然周期中 SCH 的形成无关。结论（S） 这是第一项通过 FET 协议类型评估 SCH 形成的研究。我们的结果强调，高血清雌二醇水平不会独立导致 SCH 率的增加。必须进行进一步的研究以了解自然和程序化 FET 周期准备之间的其他临床或分子差异，这些差异可以更好地与 SCH 形成相关联。