By Lisa Rapaport

(Reuters Health) – New mothers who want intrauterine devices (IUDs) for long-acting contraception after giving birth should know the risk of the implant being expelled is tied to how soon after delivery it is inserted, researchers say.

The best option is either to place the IUD immediately after delivery, when there is only a 10 percent risk of the uterus expelling the device, or to wait at least four weeks afterward, when the risk drops to 4 percent, an analysis of existing research found.

When women get an IUD implanted in the uterus more than 10 minutes after delivery but less than four weeks later, the risk of expulsion is 30 percent overall, researchers report in Obstetrics & Gynecology. With a vaginal delivery, the risk of expulsion of an IUD inserted within four weeks is also more than five times greater than with a cesarean-section delivery.

“The uterus grows during pregnancy and has to shrink back down in the weeks following delivery,” said lead study author Dr. Tara Jatlaoui of the U.S. Centers for Disease Control and Prevention in Chamblee, Georgia.

“It is that process during the postpartum period that likely increases the risk of IUD expulsion compared with IUD placement at another time,” Jatlaoui said by email.

IUDs are T-shaped devices about the size of a quarter that are inserted into the uterus. The devices can be used for several years; they prevent pregnancy by stopping sperm from reaching the egg.

While placing an IUD immediately after birth carries a slightly increased risk that it may loosen and fall out, the risks of other complications, such as infections, are small and similar to the odds of side effects from an IUD placed later in the doctor’s office.

The American College of Obstetricians and Gynecologists (ACOG) recommends that women having hospital births get the opportunity to receive long-acting birth control like IUDs before they leave the hospital. The advantage of this approach is that it may help avoid pregnancies spaced too close together, which carry a risk of serious complications for both mothers and babies.

The current study analyzed data from 48 previously published studies on the risk of IUD expulsion postpartum.

ACOG considered much of the same research when it endorsed the option of IUD placement right after delivery, noted Dr. Ann Borders of the NorthShore University HealthSystem in Evanston, Illinois, and the University of Chicago Pritzker School of Medicine.

“Many women prefer the convenience of immediate postpartum placement with high likelihood of success,” Borders, who wasn’t involved in the current study, said by email

For some women, concerns about access to care, out-of-pocket costs, and insurance coverage may influence their decision about whether or when to get an IUD, said Dr. Michelle Moniz, a researcher at the University of Michigan in Ann Arbor who wasn’t involved in the study.

Even though contraceptives are generally covered by insurance, women may still have fees for extra doctor visits needed to insert an IUD after they leave the hospital as well as for follow-up visits to make sure the IUD has remained in place.

Women who want long-acting contraception can also use hormone-releasing implants about the size of a matchstick that are inserted under the skin in the upper arm and can prevent pregnancy for several years, or they could also get contraceptive shots that last for several months.

If they choose an IUD, they should be on the lookout for problems, Moniz said by email.

“Women should be aware of the signs of IUD expulsion such as cramping, bleeding, or seeing a small T-shaped device in clothing or in the toilet,” Moniz advised. “The IUD stops working immediately if it falls out.”

SOURCE: Obstetrics & Gynecology, online October 1, 2018.