What are the possible risks of using an IUD? Abdominal pain - Following insertion, some women notice abdominal cramping pain mostly for a day or two – occasionally longer. Perforation - This is a rare but serious complication where the IUD device passes through the wall of the uterus into the pelvic area, usually at the time of, or shortly after, insertion. This may occur in about 1 per 400 insertions. This requires surgery under a general anaesthetic to remove the IUD. Some studies have found that women who have recently given birth may have an increased risk of this complication, however all women may be at risk of this rare event occurring. Expulsion - Sometimes the IUD device may be partially or completely pushed out of the uterus. It occurs in about 5 per 100 insertions and is most common in the months following insertion. It is important to regularly check for the threads, to detect if this has occurred, as the IUD won't work effectively if not fully within the uterus. Pelvic inflammatory disease (PID) - This is a rare complication of IUD insertion, most likely to occur in the first few weeks following the insertion procedure from an existing infection. It occurs in less than 1 per 300 insertions. PID may in some cases lead to infertility. Possible risks associated with ongoing use of an IUD: Miscarriage - If a pregnancy occurs in the uterus there is an increased risk of miscarriage. If the IUD is then left in place, there is an increased risk of miscarriage with infection in later stages of pregnancy or premature birth. Ectopic pregnancy - If a pregnancy does occur with an IUD in place there is a small chance the pregnancy will develop in the Fallopian tube. However, because the IUD prevents most pregnancies, it is an uncommon complication and less common than amongst women who are not using any contraception. Ectopic pregnancy is a serious condition and often requires surgical management. To reduce complications, in the rare event of a pregnancy occurring with an IUD in place, it is important to see a doctor as soon as possible if you have any reason to suspect you are pregnant, eg, if there is a change in your usual bleeding pattern; if a period is missed; is lighter than usual or you have unusual abdominal or pelvic pain.