This, they hope, will avoid some of the dangers - including Down's syndrome - of saving conception until they are ready for a child. It will be the first time such a process has been undertaken for "lifestyle" rather than reasons of infertility: neither of them wants to quit work just yet.
Although the process is virtually identical to in vitro fertilisation - which already is widely used - freezing the embryo instead of implanting it immediately reduces the chances of producing a child to a measly 12 per cent for each attempt. Thus more embryos will be lost (or killed). Also it is currently illegal to store embryos for more than five years - 10 years under extreme circumstances.
But neither of the above facts constitutes a reason why we should disapprove of this latest incidence of challenging our morality with modern technology and social change. Potential children perish every time contraception is used.
The question we should be asking is: why not? If a couple intend to raise a family, surely this is simply a sensible precaution - in the same way they might dose the mother up on folic acid, then stay fit and give up smoking in order to see their child grow up.
Logically there is no distinction between an embryo in the womb and one housed outside. And the five-year wait is immaterial philosophically: you might as well blame the doctor for spending an extra couple of minutes fiddling with her rubber gloves.