Where Do Your Eggs Go When You Have an IUD? Understanding How IUDs Work

It's a common question many people have when considering or using an Intrauterine Device (IUD): "Where do my eggs go when I have an IUD?" The simple answer is that your eggs continue to be released each month, but the IUD's presence and mechanisms prevent them from being fertilized.

Let's break down exactly what happens with your eggs and how IUDs work to prevent pregnancy.

Understanding the Menstrual Cycle and Ovulation

Before diving into IUDs, it's crucial to understand the normal menstrual cycle and ovulation:

Each month, during the follicular phase of your menstrual cycle, hormones (like Follicle-Stimulating Hormone, or FSH) stimulate the ovaries to develop several follicles.
Each follicle contains an immature egg.
As the cycle progresses, one follicle usually becomes dominant and matures fully.
Around the middle of your cycle, typically 14 days before your next period, Luteinizing Hormone (LH) surges, triggering ovulation.
Ovulation is the process where the dominant follicle ruptures and releases a mature egg from the ovary.
This egg then travels into the fallopian tube.
If sperm are present in the fallopian tube around this time, fertilization can occur, leading to pregnancy.
If fertilization doesn't happen, the egg disintegrates within 12 to 24 hours and is absorbed by the body.
The uterine lining, which has thickened in preparation for a potential pregnancy, then sheds during menstruation.

How IUDs Prevent Pregnancy

IUDs are highly effective, long-acting reversible contraceptives (LARCs) that are inserted into the uterus. They work primarily by preventing fertilization, and in some cases, by preventing implantation. There are two main types of IUDs, and their mechanisms differ slightly:

Hormonal IUDs (e.g., Mirena, Kyleena, Liletta, Skyla)

Hormonal IUDs release a progestin hormone called levonorgestrel into the uterus. Here's how they interfere with the process:

Thickening of Cervical Mucus: The progestin hormone makes the cervical mucus thicker and more viscous. This creates a barrier that makes it very difficult for sperm to travel through the cervix and into the uterus.
Thinning of the Uterine Lining (Endometrium): Hormonal IUDs can also thin the lining of the uterus. This makes it less hospitable for a fertilized egg to implant, though this is a secondary mechanism.
Inhibition of Ovulation (Less Common): In some individuals, particularly with higher doses of progestin, hormonal IUDs may suppress ovulation, meaning an egg might not be released from the ovary at all. However, for most users, ovulation still occurs regularly.

So, with a hormonal IUD, your egg is typically released from the ovary, but the thickened cervical mucus prevents sperm from reaching it in the fallopian tube. If, by chance, sperm did reach the egg and fertilization occurred, the thinned uterine lining would make implantation unlikely. If fertilization and implantation don't occur, the egg, as usual, disintegrates and is absorbed.

Copper IUDs (e.g., ParaGard)

The copper IUD does not contain hormones. It uses the presence of copper to prevent pregnancy:

Toxic to Sperm: Copper ions are released from the copper IUD and create an inflammatory reaction within the uterus. This environment is toxic to sperm, making them less mobile and less able to survive and fertilize an egg.
Altering Sperm and Egg Interaction: The copper also affects the way sperm and egg interact, further hindering fertilization.
Preventing Implantation: Similar to hormonal IUDs, the inflammatory reaction in the uterus can also make it difficult for a fertilized egg to implant, though this is considered a secondary mechanism.

With a copper IUD, your eggs are released from the ovaries as usual. However, the presence of copper in the uterus makes the environment hostile to sperm, preventing them from reaching and fertilizing the egg in the fallopian tube. If fertilization somehow did occur, the altered uterine environment would likely prevent implantation. If fertilization and implantation don't happen, the egg disintegrates and is absorbed.

In Summary: Your Eggs Are Released, But Unfertilized

The primary goal of both types of IUDs is to prevent fertilization. They achieve this by creating barriers or hostile environments that sperm cannot overcome.

"Your eggs continue to be released each month with an IUD. The IUD's job is to make sure that sperm cannot reach the egg, or if they somehow do, that fertilization or implantation cannot occur."

Therefore, when you have an IUD, your eggs are released from your ovaries, travel into your fallopian tubes, and if they are not fertilized due to the IUD's mechanisms, they simply disintegrate and are absorbed by your body, just as they would be if you weren't using any contraception and did not become pregnant that cycle.

The Menstrual Period and IUDs

The release of an unfertilized egg is what ultimately leads to your menstrual period. So, if you are still having periods with your IUD, it's a sign that ovulation is occurring and the IUD is effectively preventing pregnancy.

It's important to note that some people experience changes in their menstrual bleeding patterns with an IUD:

Hormonal IUDs: Often lead to lighter, shorter periods, or even amenorrhea (no period at all) over time.
Copper IUDs: Can sometimes make periods heavier or cause more cramping, especially in the first few months after insertion.

These changes are related to how the IUD affects the uterine lining and hormones, but they don't indicate that your eggs are being "stored" or "gone" in any way other than their normal biological fate of disintegration if unfertilized.

Frequently Asked Questions (FAQ)

How do IUDs prevent pregnancy if ovulation still occurs?

Even if ovulation occurs and an egg is released, the IUD's primary mechanisms are designed to prevent sperm from reaching the egg. For hormonal IUDs, this involves thickening cervical mucus to block sperm. For copper IUDs, the copper itself is toxic to sperm and hinders their movement. In essence, the IUD creates a formidable barrier that sperm typically cannot penetrate.

Why don't IUDs remove or store my eggs?

IUDs are placed inside the uterus, which is where a fertilized egg would implant. Eggs are released from the ovaries and travel through the fallopian tubes. The IUD does not interact with the ovaries or fallopian tubes directly in a way that would remove or store eggs. Its function is to prevent fertilization from happening in the fallopian tube or implantation in the uterus.

What happens to the egg if fertilization is prevented by the IUD?

If fertilization is prevented by the IUD, the egg continues its journey through the fallopian tube. Since fertilization hasn't occurred, the egg will eventually disintegrate and be absorbed by the body. This is the same fate an unfertilized egg would have if you were not using any contraception and did not become pregnant during that cycle. This process ultimately leads to menstruation if pregnancy does not occur.