Intrauterine devices (IUDs) are small, T-shaped contraceptive devices inserted into the uterus to prevent pregnancy. They offer a highly effective and long-acting form of birth control, known for their convenience and reliability. While IUDs are very effective, pregnancy can rarely occur, raising questions about potential outcomes like miscarriage. This article explores how IUDs function, the uncommon instances of pregnancy with them, and related medical considerations.
How IUDs Prevent Pregnancy
IUDs are highly effective, preventing pregnancy in over 99% of users. They primarily prevent fertilization or implantation of a fertilized egg. There are two main types: copper IUDs and hormonal IUDs.
Copper IUDs, like Paragard, release copper ions into the uterus. This creates an inflammatory reaction toxic to sperm and eggs, preventing fertilization and making the uterine lining unsuitable for implantation. Hormonal IUDs, such as Mirena, Kyleena, Liletta, and Skyla, release a progestin hormone called levonorgestrel. This hormone thickens cervical mucus, thins the uterine lining to prevent implantation, and can sometimes suppress ovulation.
The Rare Event of Pregnancy with an IUD
Despite their high effectiveness, pregnancy with an IUD is exceedingly rare, occurring in less than 1% of users each year. One common reason for IUD failure is partial or complete expulsion of the device from the uterus. A person might not realize their IUD has been expelled, leaving them unprotected.
Pregnancy can also occur when the IUD remains properly in place, though the exact reasons for such rare failures are not fully understood. Regular checks for the IUD strings can help confirm its proper placement and reduce the risk of unnoticed expulsion. The overwhelming majority of IUD users will never experience a pregnancy while using the device.
Miscarriage Risk with an IUD in Place
If a pregnancy occurs with an IUD in place, there is a significantly increased risk of miscarriage compared to pregnancies without an IUD. The physical presence of the IUD within the uterus can disrupt the developing pregnancy, leading to an increased likelihood of it ending spontaneously.
The risk of miscarriage is also heightened by the potential for infection. The IUD, as a foreign body, may introduce or harbor bacteria, which can lead to an intrauterine infection. Such infections pose a serious threat to the pregnancy and can result in miscarriage. Miscarriages in these circumstances can present as threatened, inevitable, or complete.
Medical Guidance and Potential Outcomes
If a person suspects pregnancy with an IUD in place, immediate medical consultation is important. Healthcare providers will confirm the pregnancy and determine its location. This assessment is vital because pregnancy with an IUD carries an elevated risk of ectopic pregnancy, where the fertilized egg implants outside the uterus, most commonly in a fallopian tube. While IUDs are highly effective at preventing intrauterine pregnancies, they do not prevent ectopic pregnancies as effectively. This means if a pregnancy occurs, it is more likely to be ectopic. Ectopic pregnancies are serious medical emergencies requiring immediate intervention, as they cannot proceed to live birth and can pose a life-threatening risk to the pregnant individual.
If the pregnancy is intrauterine and the IUD strings are visible, the healthcare provider will generally recommend removing the IUD. Removing the IUD early in the pregnancy can reduce the risk of miscarriage and infection. However, if the strings are not visible or removal is deemed unsafe, the IUD may need to remain in place, which further increases the risk of complications. Close medical supervision is essential throughout the pregnancy to monitor for signs of infection, miscarriage, or other potential issues.
If the pregnancy is intrauterine, the IUD should ideally be removed as early as possible. Removing the IUD can significantly reduce the risks of spontaneous abortion, preterm delivery, and serious infections, including septic abortion. Studies indicate that the miscarriage rate is considerably lower when the IUD is removed compared to when it is left in place. Even after IUD removal, individuals who conceive with an IUD may still face a slightly elevated risk for certain complications compared to those who conceived without an IUD.