The popular assisted reproduction technique of scratching the endometrium before implanting a fertilised egg does not improve the chances of pregnancy, a study shows. 

The technique, which is painful for women as well as being expensive, should be abandoned, according to research published in the New England Journal of Medicine. 

The method, known as endometrial scratching, involves using a flexible tube (that is also used to collect tissue samples in the uterus) to create a small scratch in the uterus lining a month or so before a fertilised egg is transferred. 

The scratch was believed to create inflammation or affect the immune system in a way that would make it easier for the egg to attach.