Professor Lyn Fraser, the chairman of ESHRE, told BBC News Online that doctors should proceed with caution.

BBC: Gene technology

Dr Edurne Novella-Maestre and colleagues from the Valencia Infertility Institute in Spain told the ESHRE conference how a new treatment might block endometriosis and the associated cancers.

BBC: NEWS | Health | Endometriosis 'ups cancer risk'

Comparing the figures released by ESHRE with those in the US is difficult, because of differences in the way they are calculated, but broadly, the US has higher "success" rates in terms of live births, but also a percentage of multiple births which is higher than the European average.

BBC: UK fertility services lag behind Europe