Freezing all embryos for later transfer might therefore improve implantation and pregnancy rates and increase the safety of IVF. Presently, the highest success rates in reproductive medicine are seen in the recipients of donor eggs. These are women who have not had ovarian stimulation - their endometrial tissue has not been exposed to high hormone levels, and they are not at risk of OHSS.
However, while the theory of a freeze-all policy seems attractive - and the technique has been commonly employed as a safety measure when OHSS is a threat - no robust systematic studies have indicated whether the cryopreservation of all viable embryos with later frozen embryo transfer (FET) is associated with better outcomes than fresh embryo transfers.
Now, the first meta-analysis on this subject indicates that the chance of a clinical pregnancy is around 30% higher when all embryos are frozen for later transfer than with fresh embryo transfer. The results were presented today at the annual meeting of ESHRE (European Society of Human Reproduction and Embryology) by Professor Miguel Angel Checa from the Hospital Universitari del Mar in Barcelona, Spain.
The study was a systematic review of the entire literature, which provided a pool of 64 relevant studies - with three randomised trials - performed before December 2011. The current review was based on information from 633 IVF/ICSI cycles in which 316 were randomised to fresh embryo transfer and 317 to FET. Results showed - based on a relative risk calculation - that the probability of a clinical pregnancy is significantly higher from freeze-all cycles than in fresh embryo transfers (a relative risk of 1.31, which was statistically significant). The miscarriage rates did not show significantly differences between the two groups.
"The pooled data demonstrates that embryo cryopreservation and subsequent FET may improve the outcome of assisted reproduction treatment," said Professor Checa. The study recorded an ongoing pregnancy rate of 38% in fresh transfer cycles, and 50% in the FET cycles.
Professor Checa also explained why FET in a later non-stimulated cycle might improve IVF results. He noted that the multiple eggs generated by ovarian stimulation will increase release of the hormone estradiol from the ovary, which affects the receptivity of endometrial tissue. In addition, some recent studies have shown that ovarian stimulation causes changes to the endometrial DNA pattern, which are not evident in the normal receptive endometrium.
Professor Checa added that the results of his study were "preliminary", but statistically robust. However, with other groups known to be performing similar studies, he urged patience until their results were known. "We are quite confident with our results," he said. "But in our view we should wait until the end of the year for results from other studies to confirm our data and recommend a change in IVF policy."
He added that, with improvements in the technologies of embryo cryopreservation (through vitrification), the evolution of freeze-thawed embryos in IVF is now comparable to that of fresh embryos. A freeze-all approach may thus extend that success even further - and with a greater degree of safety. "When we freeze all of the embryos, we completely avoid the risk of OHSS," said Professor Checa. "So freezing all the embryos we collect would avoid the biggest complication that exists in assisted reproduction."
From abstract no: O-169 Tuesday 3 July 2012, 15.30 hrs EEST
Fresh embryo transfer versus frozen-thawed embryo transfer in assisted reproduction technique cycles: a systematic review and meta-analysis
Note: When obtaining outside comment, journalists are requested to ensure that their contacts are aware of the embargo on this release.
The 28th Annual Meeting of ESHRE, the world's largest event in reproductive science and medicine, is taking place in Istanbul from 1-4 July 2012
Christine Bauquis | EurekAlert!
Tag it EASI – a new method for accurate protein analysis
20.06.2018 | Max-Planck-Institut für Biochemie
How to track and trace a protein: Nanosensors monitor intracellular deliveries
19.06.2018 | Universität Basel
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
20.06.2018 | Materials Sciences
20.06.2018 | Materials Sciences
20.06.2018 | Materials Sciences