The major disadvantage of postpartum insertion is the higher expulsion rate. The IUD is more easily expelled after childbirth because the uterus is contracting and the cervix is dilated (341). Expulsion rates following postpartum IUD insertion are lowest when the IUD is inserted within 10 minutes after the expulsion of the placenta (60, 71, 494, 498), when a copper IUD rather than an unmedicated IUD is used (382, 555, 567), and when the provider is skilled and experienced and places the IUD correctly, high in the fundus (498, 535, 555, 650). When a copper T IUD is inserted within 48 hours after delivery by an experienced provider, expulsion rates at six months range from 6 to 15 per 100 (60, 71, 382, 483, 498, 535, 561). Because insertion between one week and four to six weeks after delivery carries an increased risk of perforation, many groups advise special caution or even advise against inserting IUDs during this period (164, 398, 433, 487, 498, 535, 565).

The health care provider's skill and experience are probably more important in reducing expulsions and other complications than the type of device used (60, 361, 377, 382). A large international study of immediate postpartum insertions found that expulsion rates at three months were almost twice as high for insertions performed during the first half of the study, when the practitioners were less experienced, than in the second half (60). Similarly, a Belgian study found that rates of expulsion, accidental pregnancy, and removal for pain, bleeding, and other medical reasons were lower when postpartum insertions were performed by more experienced practitioners (382).

Insertion at cesarean section. Studies in China, Belgium, and Mexico, examining IUD insertion through the abdominal incision immediately after cesarean delivery, have found the procedure to be safe and expulsion rates to be low (59, 64, 409, 437, 524, 535, 567, 650). When there has been prolonged labor or premature rupture of the membranes, however, postcesarean insertion should be avoided because of the risk of infection (437).

Breastfeeding and IUDs. A copper or unmedicated IUD is a good contraceptive method for a lactating woman (437) because it has no effect on the quantity or composition of breast milk (53, 72). With the LNG IUD, small amounts of progestin are found in breast milk, although these low levels apparently do not affect child health (146, 531).

There has been some concern, based on a few case reports and a small case-control study, that insertion during lactation might involve a higher risk of uterine perforation (54, 144, 228, 328). Results from international clinical trials conducted by Family Health International have been largely reassuring, however. There were no instances of uterine perforation, either among the 1,243 women who were breastfeeding when the TCu-380A was inserted at least 42 days postpartum or among the 1,032 women who were not (508). Similar results were reported in clinical trials of the Gyne T-380 IUD (548). In clinical trials of the TCu-380A, Lippes Loop D, and MLCu-375 in Indonesia, there were no statistically significant differences in rates of expulsion/displacement between 724 breastfeeding women and 2,096 nonbreastfeeding women at either 12 or 24 months. All three reported perforations occurred among breastfeeding women, however (540).

Postpartum insertion requires special techniques to minimize the risk of perforation. Sounding the uterus should be avoided because of the risk of perforating the soft uterus. IUDs usually are inserted postpartum with ring forceps or by hand rather than with a standard inserter (71, 535). If the inserter is used, Tapani Luukkainen recommends that the arms of a T-shaped IUD be released from the inserter once it has passed the internal os of the cervical canal. Then the open IUD can be lifted to the fundus. The outspread arms of the T reduce the risk of perforation (608).