An Intrauterine Device (IUD) is a form of contraception placed directly into the uterus. When considering this highly effective birth control method, many people wonder how it interacts with the body’s natural reproductive cycle, specifically concerning the monthly release of an egg. Whether you continue to “lose eggs” while using an IUD depends entirely on which of the two main types you have, as hormonal and non-hormonal (copper) devices function through fundamentally different biological mechanisms.
Understanding the Natural Process of Egg Loss
The concept of “losing eggs” refers to the routine monthly process where an egg is matured and released from the ovary. This event, known as ovulation, is triggered by a surge of luteinizing hormone (LH) from the pituitary gland. Once released, the egg only remains viable for fertilization for a short window of about 12 to 24 hours as it travels down the fallopian tube.
If the egg is not fertilized, it naturally begins to degenerate. This breakdown is a biological inevitability in the absence of conception, and the remains of the egg are simply reabsorbed by the body. This process of maturation, release, and subsequent degeneration occurs nearly every month in a typical reproductive cycle.
How Hormonal IUDs Affect Ovulation
Hormonal IUDs introduce a synthetic hormone that affects the body’s signaling pathways. Progestin acts locally within the uterus, but a small amount can enter the bloodstream and influence the hormonal balance needed for the monthly preparation and release of an egg.
The primary contraceptive effect of the hormonal IUD is the thickening of cervical mucus, which physically blocks sperm from entering the upper reproductive tract. The suppression or alteration of ovulation serves as a significant secondary mechanism. By disrupting the signals that trigger the LH surge, the device can prevent the ovary from releasing a mature egg.
The extent to which ovulation is suppressed is highly dependent on the specific dosage of progestin released. For example, studies on the higher-dose 52 mg levonorgestrel IUD show that in the first year of use, only about 45 percent of users ovulate in any given cycle. This means a substantial number of individuals are not losing an egg that month because the egg is never released.
As the device remains in place, the hormone release rate gradually declines over its lifespan, which can lead to a higher rate of ovulation over time. By four years of use with the 52 mg device, studies show that approximately 75 percent of users have resumed regular or sporadic ovulation. Individuals using lower-dose hormonal IUDs are much more likely to continue ovulating throughout the device’s lifespan.
How Copper IUDs Affect Ovulation
The mechanism of action for the copper IUD is entirely different from the hormonal type, relying on a non-hormonal, localized effect within the uterus. Because this device contains no hormones, it does not interfere with the natural signaling cascade that regulates the reproductive cycle. The copper IUD does not suppress, alter, or halt the monthly process of ovulation.
Consequently, individuals using a copper IUD continue to ovulate normally every month. The natural process of egg maturation, release, and subsequent degeneration if unfertilized proceeds just as it would without contraception. In this case, the answer to the core question is definitively yes: you still lose an egg every month when using a copper IUD.
The contraceptive effectiveness of the copper IUD comes from the constant release of copper ions into the uterine and tubal fluid. These ions create an environment that is toxic to sperm. The copper ions impair the sperm’s ability to move and function, preventing them from surviving the journey through the uterus to the fallopian tube to reach the released egg. This ensures that fertilization is prevented.