An intrauterine device (20) with a restricted movement of a knot (5) of the string (4) due to a region (3) having such differed shape and size at a distal end (12) of central vertical stem (1) and due to a trajectory for string (4) in the region (3) that the length of the string (S) is shorter than the distance (r) of the region (3); and the loop (15) of the string and therefore the knot (5) is unable to pivot around the axis (14) . The lateral shift of the knot (5) is also prevented. Consequent to restricted pivoting and restricted lateral shift of the knot (5), the hanging portion (9) of the string (4) continue to project downwards and do NOT develop tendency to get retracted and thus do not curl up in the uterus (16) through the cervix (17).