Cancer
And there are also women who believe overstimulation of the ovaries through IVF may cause ovarian cancer.
Liz Tiberis, author of 'No Time to Die', believes her ovarian cancer was a result of nine attempts at IVF.
Ian Jacobs, director of the gynaecological research unit at Barts' Hospital, says there is no proof one way or the other that IVF increases a woman's risk of getting cancer.
However, he believes women should be warned that there is a possible risk.
But Professor Lord Robert Winston, a leading infertility expert, says it is "unwise" to raise the spectre of cancer unnecessarily when there is no proven risk.