Do you think your undies could be causing you serious health problems? And is there a real case for permanently consigning them to the back of your drawers? Surprising as it may seem, growing numbers of women say they are quietly giving up knickers for health reasons. It seems that synthetic materials, modern dyes and industrial- strength control fabrics now used in undies could be causing everything from infections to stomach aches and even prolapses - where an organ in a woman’s pelvis slips out of place.