Study question

研究问题

Are there differences in pregnancy outcomes when comparing frozen embryo transfer versus fresh embryo transfer among aged women?

探讨高龄妇女移植冻融胚胎与新鲜胚胎的妊娠结局是否有差异？

Summary answer

概要回答

Frozen embryo transfer yields lower live birth rate for women aged 35-39, but higher rate for women ≥40 compared to fresh embryo transfer.

与新鲜胚胎移植相比，35-39岁女性冻融胚胎移植的活产率较低，而40岁及以上女性较高。

What is known already

已知

Advanced maternal age was defined as over 35 years old, while recent literature lifted the threshold to 40. An increasing number of women are postponing childbirth, but reproductive issues become more common after the age of 35, with a significant decline in fertility, particularly after 40, even with IVF. Advanced age affects pregnancy rates, prompting some clinicians to prefer fresh embryo transfer to achieve pregnancy quickly. However, it may be less effective with potential negative effects of ovarian stimulation on endometrial receptivity. Frozen embryo transfer is seen as a better strategy, but data specific to advanced maternal age is lacking.

高龄孕产妇是指35岁以上的女性，而最近的文献将这一标准提高到了40岁。由于越来越多的女性推迟生育，生育问题在35岁以后变得更加常见。主要是生育力的明显下降，尤其是40岁以后，即使采用体外受精技术也无法改变。高龄对妊娠率的影响促使了一些临床医生倾向于选择新鲜胚胎移植，以快速实现妊娠。然而，由于卵巢刺激对子宫内膜容受性的潜在不良影响，鲜胚移植可能效果不佳，冻融胚胎移植则被视为更优方案，但对于高龄妇女目前缺乏相关数据。

Study design, size, duration

研究设计、规模、持续时间

This cohort study analyzed the Human Fertilization and Embryology Authority anonymized data from 2011 to 2018 in the United Kingdom. This comprised of a total of 232,942 cycles with advanced maternal age, in which 65,066 patients undergoing frozen embryo transfer cycles, and 167,876 patients undergoing fresh embryo transfer cycles.

这项队列研究分析了英国人类受精和胚胎学管理局（Human Fertilization and Embryology Authority） 2011—2018年的匿名数据。研究纳入了232,942个移植周期，均为高龄妇女，包括65,066个冻融胚胎移植周期，167,876个新鲜胚胎移植周期。

Participants/materials, setting, methods

研究对象/材料、背景、方法

Data on women with advanced maternal age undergoing IVF/ICSI cycles were analyzed to compare live birth rate and miscarriage rate. The cycles with patients’ age <35, donor oocyte / embryo, PGT, or without embryo to transfer were excluded. Log-binominal regression analysis was performed adjusting for patient age, cause of infertility, number of embryos transferred, year of treatment, and IVF or ICSI cycle.

分析接受IVF/ICSI周期治疗的高龄妇女相关数据，比较活产率和流产率。排除年龄<35岁、供者卵母细胞/胚胎、PGT、无胚胎移植的周期。对患者年龄、不孕原因、移植胚胎数、治疗年限以及IVF/ICSI治疗周期进行Logbinominal回归分析。

Main results and the role of chance

主要结果和偶然因素

We analyzed data from 232,942 cycles with patients age ≥35, and found that FET cycles exhibited a higher live birth rate than that of fresh embryo transfer cycles (25.5% vs. 24.9%, RR, 1.03; 95% CI, 1.01–1.123). Miscarriage rate (4.6% vs. 3.3%, RR, 1.41; 95% CI, 1.35–1.48) was also different. However, the adjusted RR (aRR) of live birth rate was 0.91; 95% CI, 0.88–0.93, after adjusting for potential confounders. For those patients aged 35-39, live birth rate (28.4% vs. 29.7%, aRR, 0.86; 95% CI, 0.83–0.88) following FET cycles was lower than that of fresh embryo transfer cycles. While FET cycles showed a higher rate of miscarriage (4.6% vs. 3.2%, aRR, 1.83; 95% CI, 1.70–1.98). When patients age≥40, FET cycles showed a higher rate of live birth (18.2% vs. 14.0%, aRR, 1.24; 95% CI, 1.16–1.32) and miscarriage rate (4.7% vs. 3.4%, aRR, 1.72; 95% CI, 1.52–1.94). Besides the live birth rate was sharply decreased than patients aged 35-39 both in FET and fresh embryo transfer cycles.

我们分析了232,942个周期，年龄≥35岁妇女的数据，发现冻融胚胎移植周期的活产率高于新鲜胚胎移植周期（分别是25.5%和24.9%，RR 1.03；95% CI 1.01-1.123），流产率也不同(分别是4.6%和3.3%，RR, 1.41；95% CI,1.35-1.48)。校正潜在混杂因素后，活产率的调整后相对危险度（aRR）为0.91，95% CI为0.88 -0.93。对35-39岁的患者，冻融胚胎移植周期的活产率低于新鲜胚胎移植周期（分别是28.4%和29.7%,aRR 0.86;95% CI, 0.83-0.88），且流产率更高(分别是4.6%和3.2%,aRR, 1.83；95% CI, 1.70-1.98)。当年龄≥40岁时，冻融胚胎移植周期有更高的活产率(分别是18.2%和14.0%，aRR 1.24；95% CI, 1.16-1.32)和流产率(分别是4.7%和3.4%,aRR, 1.72；95% CI, 1.52-1.94)，此外，其活产率，无论冻融胚胎移植和新鲜胚胎移植的活产率均显著低于35-39岁女性。

Limitations, reasons for caution

局限性及注意事项

The conclusion of the present study might be limited by the anonymous nature of the dataset. Further randomized trials may be required to provide direct evidence for the best embryo transfer strategy for the advanced age women.

本研究的结论可能受到数据集匿名性质的限制。可能需要进一步的随机试验，以提供针对高龄女性最佳胚胎移植策略的直接证据。

Wider implications of the findings

研究结果的更广泛影响

The study shows that FET exhibited a higher live birth rate in women aged ≥ 40, but lower for those aged 35-39 than fresh embryo transfer. Additionally, FET demonstrated a higher miscarriage rate. Therefore, it is necessary to tailor the embryo transfer strategy for advanced maternal age women.

研究表明，冻胚移植（FET）在年龄≥40岁的女性中表现出更高的活产率，但在35-39岁女性中则低于新鲜胚胎移植。此外，FET还显示出更高的流产率。因此，有必要为高龄产妇量身定制胚胎移植策略。

参考文献：

Z Wang, C Liu, N Kong, G Yan, H Sun, O-207 Comparison of the pregnancy outcomes of transferring frozen embryos versus fresh embryos among advanced maternal age women: a nationwide analysis of 232,942 cycles, Human Reproduction, Volume 39, Issue Supplement_1, July 2024, deae108.240, https://doi.org/10.1093/humrep/deae108.240