Almost every day a scientific or medical development seems to bring new promise and controversy to mankind; none more so, perhaps, than in the field of human fertility.A quarter of a century ago the first test-tube baby, Louise Brown, was born. Now scientists have raised another startling prospect - "unborn mothers".The notion that children can derive from human matter that has not itself been born sounds the stuff of science fiction. Yet it has moved a step closer with research showing that it is possible to extract ovarian tissue from aborted foetuses for in-vitro fertilisation (IVF) treatment.Scientists announced yesterday that...