An IUD (intrauterine device) is a small, flexible contraceptive device that is shaped like the letter T and is inserted into the uterus. This contraceptive method is long-lasting, safe, and extremely effective. There are two IUD types of IUDs available:
- Mirena IUD: Made of a soft, flexible plastic, Mirena releases a low amount of the progestin levonorgestrel continuously over a 5-year period as one way to prevent pregnancy.
- ParaGard IUD: Also called the Copper T 380A, it is made of flexible plastic and wrapped in copper. Unlike Mirena, it is hormone-free. ParaGard releases a tiny amount of copper over a 10-year period as one way to prevent pregnancy.
IUDs are one of the most effective reversible methods of birth control available. The Mirena IUD is 99.9% effective, while ParaGard is 99.2-99.4% effective. This means that out of every 100 women who these IUDs in one year, less than one will become pregnant with typical use as well as with perfect use. Although these numbers are very promising, IUDs are not foolproof. This means that less than 1% of the time, a woman will have an IUD pregnancy.
If you think that you are experiencing an IUD pregnancy, the first thing you should do is confirm that you are pregnant. You can take a home pregnancy test or schedule a blood pregnancy test with your doctor. If you have indeed become pregnant while your IUD is still in place, your doctor will recommend that the IUD be removed. Although some women choose to continue an IUD pregnancy with the IUD in place, there are several reasons why it is healthier and safer to have the IUD removed.
Miscarriage and IUD Pregnancy
Women who are experiencing an IUD pregnancy are more likely to miscarry than women who did not have an IUD in place at conception. In a normal pregnancy, the miscarriage rate is about 18-20%. If you choose to leave the IUD in, your miscarriage rate increases to about 50%. Removing the IUD early in a pregnancy reduces the risk of miscarriage to about 25%.
However, it is important to note that the process of removing the IUD can also cause a miscarriage -- though the risk of miscarriage is lower if you have the IUD removed as soon as a pregnancy is confirmed, the risk is still higher than that of women without an IUD. As your IUD pregnancy progresses, your risk for miscarriage is lower if you have the IUD removed rather than leave it in place.
IUD Pregnancy and Preterm Birth
Leaving an IUD in place during the pregnancy increases the likelihood of preterm delivery. Women who have IUDs in place during their pregnancies are up to four times more likely to deliver their baby prematurely than women without an IUD in place. Additionally, because of the progestin released by Mirena, should a woman choose to continue her pregnancy with her Mirena IUD in place, the long-term effects on the baby are not yet known.
Ectopic IUD Pregnancy
The use of IUDs is considered to be a risk factor for future ectopic pregnancy (a pregnancy where the egg implants outside of the uterus). In the general population, ectopic pregnancies occur an estimated 2% of the time. However, if you become pregnant while your IUD is in place, the risk that you will have an ectopic pregnancy is higher. That risk ranges from 6% to as high as 50%.
IUD Pregnancy and InfectionThere is always the possibly that an infection can occur in women who have IUDs. Women who choose to keep their IUDs intact may increase their chance of intrauterine infection, sepsis, and septic second-trimester fetal loss. Sepsis is a potentially dangerous or life-threatening medical condition with the majority of sepsis cases being due to bacterial infections.
Women who become pregnant with an IUD in place and choose not to remove it during the first trimester of their pregnancy are at a greater risk of septic second-trimester fetal loss (miscarriage). Many of these septic losses are particularly unpleasant and, in some cases, can be associated with subsequent infertility.
Finally, though extremely rare, maternal deaths have been reported during the second trimester of pregnancy due to infection when an IUD has not been removed during the pregnancy.
Foreman, H., Stadel, B., & Schlesselman, S. (1981) Intrauterine Device Usage and Fetal Loss. Obstetrics & Gynecology, 58(6):669-677. Accessed via private subscription.
Grimes, DA (2004). Intrauterine devices (IUDs). In RA Hatcher et al., eds., Contraceptive Technology, 18th ed., pp. 495–530. New York: Ardent Media.