They found that the gene's activity rose and fell at a steady pace in both unfertilised and fertilised eggs.
BBC: Body clock 'set before birth'
2.
However it has a lower success rate than conventional assisted conception techniques, such as IVF, because ice crystals can form inside the unfertilised egg and damage its contents.
BBC: NEWS | UK | England | West Midlands | Clinic creates frozen egg twins
3.
This technique involves inserting unfertilised eggs, and sperm, into the fallopian tubes, and is not currently covered by guidance, so in theory any number of eggs could be used.