An intrauterine device (IUD) with a restricted movement of a string(s), the strings can be either a single string or two or more strings or a filament, emerging from the spherical bulge of IUD. The strings of IUD are of a differential strength so that the strings are soft and the hanging portion of the strings, “feelable” in the vaginal cavity, does not cause discomfort to the woman, nor bruise the organ of the partner during intercourse, at the same time the strings in the endocervical canal are relatively stiffer and not have the tendency to get curled up progressively. The strings optionally have marks to facilitate cutting by a surgeon to an accurate length.