A revolutionary method for detecting which human embryos are most likely to develop successfully to the stage at which they implant in the womb has been developed by scientists at the University of York and clinicians at Leeds General Infirmary.
The research was funded by the UK Medical Research Council.
The discovery, if confirmed in clinical trials, could bring new hope for many couples undergoing fertility treatment, since current failure rates are high.
One of the problems is that embryos for replacement in the womb are currently judged by eye under the microscope, but this method has not proved particularly successful in predicting their potential to give rise to a pregnancy.
The new method was developed by Professor Henry Leese and colleagues in the Department of Biology at the University of York, together with members of the IVF Unit (In Vitro Fertilization) at Leeds General Infirmary.
Two days after fertilization, embryos are placed in a culture medium containing amino acids and monitored in the laboratory to see how they consume or produce these amino acids.
Professor Leese said, “We’ve found a marked difference between the embryos which develop successfully in culture and those which do not. The healthy embryos have a 'quieter' metabolism.
"The method is completely non-invasive and does not harm the embryos in any way. It opens up the prospect of selecting high-quality embryos to replace into the womb, increasing success rates, reducing the financial and emotional cost to patients and greatly eliminating the risk of multiple births.
"If all goes well with the clinical trials, we hope to have a diagnostic test for use in clinics in two or three years' time.”
Professor Leese is a member of the Human Fertilization and Embryology Authority (HFEA) which regulates, licenses and collects data on fertility treatments such as IVF and donor insemination, as well as human embryo research, in the UK.
The work, published in the journal Human Reproduction, used embryos donated for research.
IVF (In Vitro Fertilization or test-tube fertilization) has helped many thousands of couples worldwide to conceive, but success rates are low - the Human Fertilization and Embryology Authority’s Annual Report showed an 18.2% live birth rate per treatment cycle in the UK in 2000.
Multiple births are associated with prematurity, increased neonatal and maternal mortality and child handicap.
The team at York includes Dr. Franchesca Houghton, Judith Hawkhead and Peter Humpherson.
The team of clinicians at Leeds General Infirmary includes Tony Rutherford and Adam Balen, Consultants in Obstetrics and Gynecology, and Jan Hogg, Senior Embryologist.
(Reference: Human Reproduction, volume 17, pp 999-1005, 2002.)
The University of York