Many clinical interventions used during in-vitro fertilization (IVF), including ultrasound guidance at the time of embryo transfers appear to increase pregnancy rates, however prolonged bed rest should not be recommended, finds a new study led by UCL researchers.
The research team from UCL, University College London Hospitals NHS Foundation Trust (UCLH), the University of Birmingham and University Hospitals Coventry and Warwickshire NHS Trust undertook a comprehensive review to investigate the effectiveness of 38 different interventions performed at the time of embryo transfer.
IVF involves several integrated stages: stimulating the ovaries to obtain several eggs; fertilising the eggs to form embryos in the lab; and finally, transferring an embryo back to the mother's womb. The process of embryo transfer is particularly delicate as optimal conditions need to be in place to maximise the chances of an embryo implantation and clinical pregnancy.
Analyzing data from 188 randomized controlled trials involving more than 59,530 participants, the study found that performing an embryo transfer under ultrasound guidance increased the chances of pregnancy by 26%.
Other promising interventions included the use of soft embryo transfer catheters, which may cause less trauma to the lining of the womb, compared to hard ones (12% improvement), and using a substance called hyaluronic acid could also help improve embryo implantation in the womb.
The peer-reviewed study, published in Human Reproduction Update, importantly found that prolonged bed rest (for more than 20 minutes) immediately after embryo transfer was associated with a 15% reduction in the chances of clinical pregnancy. The findings suggest women should be encouraged to continue in their routine daily activities after the embryo transfer procedure.
This is the first study to present a comprehensive overview of all interventions offered to couples undergoing IVF to help us decide what is the best practice when performing an embryo transfer.
It is reassuring to see that some of the interventions that are used regularly in the UK, such as using ultrasound guidance and soft embryo transfer catheters, appear to increase the likelihood of pregnancy.
We also identified several promising interventions around the time of embryo transfer such as the use of the drug Atosiban and pregnancy hormone HCG that could help to improve the chances of embryo implantation. These drugs seem to improve the womb receptivity of the transferred embryo, however, we need larger studies to accurately evaluate how effective and safe these inventions are. We call on major health funders to urgently invest in IVF research to help couples in need to help them start a family.''
Dr Bassel H. Al Wattar, Lead Author, UCL Institute for Women's Health and UCLH Reproductive Medicine Unit
Dr H. Al Wattar added: "While the current body of evidence remains imprecise for these additional interventions, they should not be offered routinely to all couples undergoing IVF pending further research to evaluate their effectiveness and safety."
Recommending bed rest post-embryo transfer was the only intervention in this review that significantly reduced clinical pregnancy rates, and this is consistent with guidance from the American Society for Reproductive Medicine (ASRM).
Dr H. Al Wattar concluded: "IVF is becoming a standard treatment worldwide to help millions of couples start their family life and get pregnant.
"As many couples are subjected to additional interventions at great cost, both from health and financial perspectives, there is a crucial need for comprehensive high-quality research to identify the best interventions that can be used to optimise the IVF process."
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