Scientists could be given permission to genetically modify human embryos for the first time in the UK when controversial proposals go before the fertility regulator on Thursday.
The Human Fertilisation and Embryology Authority (HFEA) is to consider an application from the Francis Crick Institute in London to alter genes in a bid to reduce miscarriages and infertility.
Dr Kathy Niakan, who is leading the research, said: "This is important because miscarriages and infertility are extremely common but not very well understood.
"You never can predict where the research will lead but we hope it would be a great benefit for fertility treatments in the long-term."
Dr Niakan's team wants to understand the early stages of human development by studying embryos, "surplus to requirement" from IVF treatment and donated by willing couples, during the first week of development.
The process would take place before the fertilised egg implants and examine how one cell - a zygote - on day one develops into a 64 to 256 cell blastocyst on days five to seven.
Each one would then be destroyed and not implanted.
Dr Niakan said in the long-term the research could mean the embryo with the greatest chance of developing could be implanted or genetics could be "tweaked" to maximise an embryo's chance of survival.
The researchers want to alter genetics from day one using crispr cas 9 - a new method "like molecular scissors" which they say is "most efficient and most precise" and "80 to 100%" successful.
For the pilot, Dr Niakan wants to target three to four genes using 20 to 30 embryos per experiment, which means the most initial research would require is 120.
The process has been tried on both monkeys and mice but Dr Niakan said there are differences between the embryos of a human and a mouse that make experimenting on human embryos necessary.
She said: "The reason why I think this research is so important is many groups have reported that similar to IVF embryos, even outside of IVF, most human embryos fail to reach the blastocyst stage. And of those that do reach the blastocyst stage will fail to implant."
She referred to IVF figures that showed of 100 fertilised eggs (zygotes), fewer than 50 became blastocysts, only 25 implanted and only 12 to 13 continued to develop beyond three months.
The proposals have been met with resistance from pro-life groups.
A Comment on Reproductive Ethics spokeswoman said the group was "opposed to any form of destructive research on human embryos".
After the HFEA meeting, the proposals will be considered by an ethics committee. If approved Dr Niakan said she hoped it would be a matter of "months" before the research could start.