Mount Sinai Fertility, 250 Dundas St. W, Suite 700, Toronto, Ontario, Canada.
Department of Obstetrics and Gynecology, Mount Sinai Hospital, 600 University Ave., University of Toronto, Toronto, Ontario, Canada.
Hum Reprod. 2018 Oct 1;33(10):1883-1888. doi: 10.1093/humrep/dey281.
Does each millimeter decrease in endometrial thickness lead to lower pregnancy and live birth rates in fresh and frozen IVF cycles?
Clinical pregnancy and live birth rates decline as the endometrial thickness decreases below 8 mm in fresh IVF-ET and below 7 mm in frozen-thaw embryo transfer (ET) cycles.
Previous studies have been heterogenous and have shown conflicting results on the impact of endometrial thickness on IVF outcomes. Most studies do not include many patients with an endometrial thickness below 6 mm, and there are few studies of frozen-thaw ET cycles.
STUDY DESIGN, SIZE, DURATION: This study is a retrospective cohort analysis of all Canadian IVF fresh and frozen-thaw ET cycles from the CARTR-BORN database for autologous and donor fresh and frozen-thaw IVF-ET cycles from 1 January 2013 to 31 December 2015. A total of 24 363 fresh and 20 114 frozen-thaw IVF-ET cycles were reported during this timeframe.
PARTICIPANTS/MATERIALS, SETTING, METHODS: 33 Canadians clinics participated in voluntary reporting of IVF and pregnancy outcomes to the CARTR-BORN database. The impact of endometrial thickness on pregnancy, live birth and pregnancy loss rates were analyzed for fresh IVF-ET and frozen-thaw cycles.
In fresh IVF-ET cycles, clinical pregnancy and live birth rates decreased (P < 0.0001) and pregnancy loss rates increased (P = 0.01) with each millimeter decline in endometrial thickness below 8 mm. Live birth rates were 33.7, 25.5, 24.6 and 18.1% for endometrial thickness ≥8, 7-7.9, 6-6.9 and 5-5.9 mm, respectively. In frozen-thaw ET cycles, clinical pregnancy (P = 0.007) and live birth rates decreased (P = 0.002) with each millimeter decline in endometrial thickness below 7 mm, with no significant difference in pregnancy loss rates. Live birth rates were 28.4, 27.4, 23.7, 15 and 21.2% for endometrial thickness ≥8, 7-7.9, 6-6.9, 5-5.9 and 4-4.9 mm, respectively. The likelihood of achieving an endometrial thickness ≥8 mm decreased with age (89.7, 87.8 and 83.9% in women <35, 35-39 and ≥40, respectively) (P < 0.0001).
LIMITATIONS, REASONS FOR CAUTION: This study only included cycles which proceeded to ET, which may overestimate pregnancy outcomes. Approximately 8% of cycles could not be included in the analysis due to data irregularity related to data entry. Demographic data aside from age were unavailable but may be important as lower endometrial thickness may be associated with poor ovarian response.
Although pregnancy and live birth rates decrease with endometrial thickness, reasonable outcomes were obtained even with lower endometrial thickness measurements. These data provide valuable guidance for both physicians and patients when confronted with decisions related to a persistently thin endometrium.
STUDY FUNDING/COMPETING INTEREST(S): This study was not funded. The authors do not have any conflicts of interests to declare.
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子宫内膜厚度每减少 1 毫米是否会降低新鲜和冷冻体外受精（IVF）周期的妊娠和活产率？
在新鲜 IVF-ET 中，当子宫内膜厚度降至 8 毫米以下，在冷冻胚胎移植（ET）周期中降至 7 毫米以下时，临床妊娠和活产率下降。
之前的研究存在异质性，并且对子宫内膜厚度对 IVF 结果的影响存在相互矛盾的结果。大多数研究没有包括许多子宫内膜厚度低于 6 毫米的患者，并且很少有冷冻胚胎移植周期的研究。
研究设计、大小和持续时间：这是一项对 2013 年 1 月 1 日至 2015 年 12 月 31 日期间来自加拿大的所有自体和供体新鲜和冷冻解冻 IVF-ET 周期的加拿大 IVF 新鲜和冷冻解冻 ET 周期的回顾性队列分析。在此期间共报告了 24363 个新鲜周期和 20114 个冷冻解冻 IVF-ET 周期。
参与者/材料、设置、方法：33 家加拿大诊所自愿向 CARTR-BORN 数据库报告 IVF 和妊娠结局。分析了新鲜 IVF-ET 和冷冻解冻周期中子宫内膜厚度对妊娠、活产和流产率的影响。
在新鲜的 IVF-ET 周期中，临床妊娠率和活产率下降（P < 0.0001），流产率上升（P = 0.01），子宫内膜厚度每减少 1 毫米。活产率分别为≥8mm 时为 33.7%、25.5%、24.6%和 18.1%，7-7.9mm 时为 6-6.9mm 时为 24.6%和 18.1%，6-6.9mm 时为 24.6%和 18.1%，5-5.9mm 时为 18.1%。在冷冻解冻 ET 周期中，临床妊娠率（P = 0.007）和活产率（P = 0.002）随着子宫内膜厚度每减少 1 毫米而下降，流产率无显著差异。活产率分别为≥8mm 时为 28.4%、27.4%、23.7%、15%和 21.2%，7-7.9mm 时为 27.4%、23.7%、15%和 21.2%，6-6.9mm 时为 23.7%、15%和 21.2%，5-5.9mm 时为 15%和 21.2%，4-4.9mm 时为 15%和 21.2%。获得子宫内膜厚度≥8mm 的可能性随着年龄的增长而降低（<35 岁、35-39 岁和≥40 岁的女性分别为 89.7%、87.8%和 83.9%）（P < 0.0001）。
局限性、谨慎的原因：本研究仅包括进行 ET 的周期，这可能高估了妊娠结局。由于与数据录入相关的数据不规则性，约 8%的周期无法纳入分析。除年龄外，没有可用的人口统计学数据，但可能很重要，因为较低的子宫内膜厚度可能与卵巢反应不良有关。
尽管子宫内膜厚度与妊娠和活产率呈负相关，但即使子宫内膜厚度较低，仍能获得合理的结果。这些数据为医生和患者在面对与持续薄子宫内膜相关的决策时提供了宝贵的指导。
研究资助/利益冲突：本研究没有得到资助。作者没有任何利益冲突要声明。
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