A serious blunder at one of Britain's top fertility clinics dramatically increased the risk its patients would suffer a miscarriage or give birth to a child with serious health problems, sparking fresh fears about how IVF centres are run in the wake of a series of scandals. Unscreened sperm used by staff at the London Women's Clinic (LWC) to create dozens of embryos was later found to have a chromosome abnormality that could have been passed on to any unborn child, The Independent on Sunday has learnt. The British Fertility Society's screening guidelines make it clear that the clinic should never have accepted the donor. At least one couple suffered a miscarriage as a direct result.