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expert reaction to unpublished conference abstract about frozen embryos in IVF and maternal hypertension

A conference abstract, presented at the European Society for Human Reproduction and Embryology (ESHRE) Annual meeting, discusses frozen embryos in IVF and maternal hypertension.


Prof Daniel Brison, Scientific Director of the Department of Reproductive Medicine, University of Manchester, said:

“This research is being presented in preliminary form at a conference, which means it has not been peer reviewed and the important details of exactly how the study has been conducted are not available, therefore it is not possible to comment on the validity of the findings. 

“Having said that, this is a top class research group using a large and well established registry which has been used in the past for much valuable research on assisted reproductive technology (ART), so the findings are worthy of serious note.  The implications are important as women and their partners need to be made aware of any potential risks of ART treatment including an increased risk of pre-eclampsia. 

“As the authors correctly point out, this increased risk needs to be set in the wider context of risks of ART treatment.  Frozen embryo transfer can reduce the risk of other complications of ART such as multiple births, and research on UK ART children carried out here at the University of Manchester has shown that children born from frozen embryo transfer have a growth profile which resembles naturally conceived children more closely than do children from fresh embryo transfer.  The biological mechanisms underlying any of these effects are unclear, they could include epigenetic changes to the embryo, as the authors suggest, or changes which occur at the earliest stages of implantation when the embryo interacts with the maternal environment.”


Dr Ying Cheong, Professor of Reproductive Medicine at the University of Southampton, said:

“The association between frozen embryo cycles and hypertensive disease in pregnancy has been known for a while, and there is still currently an active debate around the pros and cons of ‘Freeze all for all?’ amongst fertility doctors. There are two important points to take home here, firstly, whilst frozen embryo transfer technology has transformed reproductive medicine, FET must only be performed where clinically appropriate and secondly, clinicians and scientists need to start joining the dots between what happens at early development and later at birth and beyond, a research area, in my opinion, that is still poorly supported and studied.”




‘Frozen embryo transfers in IVF linked to greater risk of maternal hypertension in pregnancy’ was presented by Dr Sindre Petersen at ESHRE – the embargo lifted at 10.15am UK time on Wednesday 6 July 2022.



Declared interests

Prof Brison: I am employed as a consultant embryologist by Manchester University NHS Trust which delivers clinical ART services, and I also hold grants via the University of Manchester to carry out research into the health outcomes of ART children. 

No others received.


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