Dr Wells said: 'You can imagine the pressure felt by an IVF patient who's struggled for years to achieve a pregnancy and then discovers they are pregnant but the baby has something like Down's.'

The conference will also hear the results of a California University study which found that women on their third IVF cycle were no more likely to conceive than those receiving no treatment.

Five other women, all of whom have a history of unsuccessful IVF treatment, are now pregnant after receiving the treatment.