New mothers who want to use intrauterine devices (IUDs) for long-acting contraception after giving birth should know the risks of expulsion associated with when the device is implanted, researchers say.

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.

When is best?

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 Caesarean section.

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

“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.

Placing an IUD immediately after birth carries a slightly increased risk that it may loosen and fall out, but 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.

Why use birth control right after giving birth?

The American College of Obstetricians and Gynecologists (ACOG) recommends that women having hospital births get the opportunity to receive a long-acting birth control such as an IUD 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, said Ann Borders, a medical doctor with the NorthShore University HealthSystem in Evanston, Ill. She is also with 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.

Are IUDs expensive?

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 Michelle Moniz, a medical doctor and researcher at the University of Michigan in Ann Arbor who wasn’t involved in the study.

Contraceptives are generally covered by insurance, but 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.

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