An Intrauterine Device (IUD) is a highly effective, long-acting reversible contraceptive method placed inside the uterus by a healthcare provider. The device, typically T-shaped, works by preventing fertilization or implantation, offering protection for several years. IUDs are categorized into two types: those that release hormones and those that use copper. Whether an IUD can cause a late or missed period depends entirely on which type is used, as they alter the menstrual cycle through different biological mechanisms.
Hormonal IUDs and Period Suppression
Hormonal IUDs contain levonorgestrel, a synthetic form of progesterone, which is released directly into the uterine cavity. This progestin acts locally to prevent the normal buildup of the endometrium, the lining of the uterus shed during menstruation. The constant, low-dose exposure suppresses the proliferation of endometrial tissue, causing it to become thinner.
Since a period is the shedding of this lining, a thinned lining means there is little material to shed. This frequently results in lighter and shorter periods, a condition known as oligomenorrhea. For many users, this progresses to amenorrhea, the complete absence of a menstrual period. After one year of use, 20% to 50% of individuals may stop having periods entirely, which is a normal and safe side effect.
During the first three to six months after insertion, irregular bleeding or spotting is common as the body adjusts to the local progestin. This initial unpredictability can be mistaken for a late or missed period because the timing of the flow is erratic. Once the adjustment period is over, a missed period is often a sign that the IUD is working as intended by maintaining a suppressed endometrial state.
Copper IUDs and Menstrual Changes
The copper IUD is non-hormonal and does not release progestin or thin the uterine lining. Since it is hormone-free, it does not suppress ovulation or alter the body’s natural hormonal cycle, meaning a regular period should continue. Its primary contraceptive mechanism involves the copper creating a local inflammatory response within the uterus that is toxic to sperm and eggs, preventing fertilization.
The inflammatory reaction often leads to an increase in menstrual flow and duration. Many users experience heavier bleeding (menorrhagia) and more pronounced cramping, particularly in the initial months following insertion. The total volume of blood loss can increase by up to 50% compared to pre-IUD periods.
A late or missed period is not an expected side effect with a copper IUD because the device does not interfere with the hormonal cycle. If a period is late, other factors are likely responsible, such as stress, illness, or substantial changes in weight or exercise. Therefore, a missed period while using a copper IUD should be treated as potentially significant, not merely a device side effect.
When to Consult a Healthcare Provider
A late or missed period always requires attention to rule out pregnancy, even if using a hormonal IUD where absence of bleeding is common. IUDs are highly effective, but a pregnancy test should be taken if a period is missed for six weeks or more. If the test is positive while the IUD is inserted, immediate medical consultation is required due to the risk of an ectopic pregnancy. An ectopic pregnancy, where the fertilized egg implants outside the uterus, is a serious complication.
Warning Signs and Complications
Certain symptoms, regardless of the IUD type, necessitate prompt medical evaluation. These signs indicate a potential complication, such as infection or displacement.
- Severe, persistent pelvic pain or cramping that is worse than expected menstrual pain.
- Fever or chills.
- Unusual, foul-smelling vaginal discharge, which can indicate an infection like Pelvic Inflammatory Disease.
Checking IUD Strings
It is important to regularly check for the IUD strings, which protrude slightly from the cervix. If the strings feel shorter, longer, or cannot be felt at all, the IUD may have shifted or been partially expelled. A displaced IUD may not be fully effective and can cause discomfort, requiring a healthcare provider to check the position and ensure continued contraceptive protection.