The NPEU Clinical Trials Unit is collaborating with the University of Aberdeen on a large-scale multi-centre trial comparing the use of ‘fresh’ and frozen embryos for IVF, the first of its kind in the UK. E-Freeze, funded by the NIHR Health Technology Assessment (HTA) Programme will recruit 1,086 couples to see which method produces the greatest number of healthy babies, as well as considering the health of the mother and costs to the health services and longer-term societal costs.