Early copper IUDs had copper around only the vertical stem, but more recent models have copper sleeves wrapped around the horizontal arms as well, increasing effectiveness. Some newer models also contain a silver core instead of a plastic core to delay copper fragmentation as well as increase the lifespan of the device. The lifespan of the devices range from 3 years to 10 years; however, some studies have demonstrated that the TCu 380A may be effective through 12 years. Its ATC code is . The copper IUD must be inserted by a qualified medical practitioner. A copper IUD can be inserted at any phase of the menstrual cycle, but the optimal time is right after the menstrual period, when the cervix is softest and the woman is least likely to be pregnant. The insertion process generally takes five minutes or less. The procedure can cause cramping or be painful for some women. Before placement of an IUD, a medical history and physical examination by a medical professional is useful to check for any contraindications or concerns. It is also recommended by some clinicians that patients be tested for gonorrhea and chlamydia, as these two infections increase the risk of contracting pelvic inflammatory disease shortly after insertion. Immediately prior to insertion, the clinician will perform a pelvic exam to determine the position of the uterus. After the pelvic exam, the vagina is held open with a speculum. A tenaculum is used to steady the cervix and uterus. Uterine sounding may be used to measure the length and direction of the cervical canal and uterus in order to decrease the risk of uterine perforation. The IUD is placed using a narrow tube, which is inserted through the cervix into the uterus. Short monofilament plastic/nylon strings hang down from the uterus into the vagina. The clinician will trim the threads so that they only protrude 3 to 4 cm out of the cervix and remain in the upper vagina. The strings allow the patient or clinician to periodically check to ensure the IUD is still in place and to enable easy removal of the device. The copper IUD can be inserted at any time in a woman's menstrual cycle as long as the woman is not pregnant. An IUD can also be inserted immediately postpartum and post-abortion as long as no infection has occurred. Breastfeeding is not a contraindication for the use of the copper IUD. The IUD can be inserted in women with HIV or AIDS as it does not increase the risk of transmission.