Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus. As the condition progresses, these growths can damage the surrounding reproductive organs, impacting fertility.

A type of tissue called endometrium lines the inside of the uterus. Throughout each month, the lining gets thicker, and it is at its thickest right before ovulation.

In a person with endometriosis, the abnormal tissue that grows outside the uterus behaves similarly. It thickens before ovulation, and during menstruation, it swells and bleeds into areas it should not be.

This swollen tissue may block the fallopian tubes or grow into the ovaries, which can make it more difficult for a person to get pregnant.

Read more about the link between endometriosis and infertility, how a person can manage the condition, and fertility treatment options for those trying to conceive.

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Although endometriosis does not necessarily cause infertility, it can reduce fertility in many people. This does not mean individuals with endometriosis cannot get pregnant — instead, it means they may have a more challenging time getting pregnant.

Experts estimate that about half of women with infertility also have endometriosis.

Endometriosis is a progressive condition, which means it can gradually worsen over time. As more and more patches of endometriosis tissue grow in the pelvic and abdominal areas, they can block the reproductive organs. This makes it harder for sperm to reach the egg.

Additionally, these growths can damage the reproductive organs, preventing them from working properly.

Endometriosis can also affect fertility by:

  • preventing an embryo from implanting
  • scarring the fallopian tubes
  • affecting egg growth
  • creating a hormonal imbalance
  • causing chronic inflammation in the pelvis

There are three main types of endometriosis: superficial peritoneal, endometriomas, and deeply infiltrating. These classifications describe where the endometriosis patches have grown in a person’s body.

A person can have one or multiple types.

Additionally, medical professionals divide endometriosis into stages. They range from I–IV, with stage I being the least severe and stage IV the most severe.

Superficial peritoneal

The peritoneum is a thin film lining the abdomen. When a person has a peritoneal lesion, they may have growths or cysts in the peritoneum.

Doctors usually class superficial peritoneal lesions as stage I or II endometriosis. Despite superficial peritoneal lesion being the least severe form of endometriosis, some people may find conceiving difficult.


Endometriomas are cysts that grow on the surface of or inside the ovaries. They are dark, fluid-filled sacs that doctors sometimes refer to as chocolate cysts.

When a person has endometrioma, they usually have stage III or IV endometriosis. This means they may begin developing scar tissue on the fallopian tubes and ovaries.

Endometriomas can greatly impact a person’s fertility due to their damaging effect on ovarian tissue, which may lead to ovulation issues.

Deeply infiltrating

In deeply infiltrating endometriosis, endometrial-like tissue grows on organs near the uterus, such as the vagina, bladder, and bowel. It is the most severe form of the condition.

Doctors usually classify deeply infiltrating endometriosis as stage IV because a person has growths or lesions that extend 5mm below the peritoneum. In addition to endometriomas, a person with stage IV endometriosis may have extensive scarring in the ovaries, uterus, and rectum.

If a person has already undergone previous cyst removal surgeries, they may have also lost a significant number of eggs.

It is important to note that while a person may no longer be able to conceive naturally at this stage, they may become pregnant with IVF treatment.

If a person with endometriosis wants to conceive, a doctor may evaluate their condition using the endometriosis fertility index (EFI).

The EFI is a 10-point scale that can tell a doctor how likely a person is to get pregnant without medical intervention. The scale considers factors including:

  • age
  • endometriosis stage
  • least function score (measures fallopian tube and ovarian function)
  • length of infertility
  • medical history
  • prior pregnancies

A person’s score can predict their likelihood of getting pregnant, and it can help individuals and doctors make the best decisions for their fertility.

Although recommendations vary from person to person, a 2021 study concluded that people with scores of 5 or higher might be able to try conceiving naturally for 24 months before medical intervention. The authors said that those with scores of 4 or lower should be referred for artificial reproductive treatments more quickly.

Several treatment options are available for people with endometriosis who have not become pregnant after 6–12 months of trying.

The treatment a doctor recommends depends on the stage and type of endometriosis a person has.

Treatments for stages I–II

In the earlier stages of endometriosis, a person might be able to get pregnant without any medical assistance.

However, if someone is finding it difficult to conceive, a doctor may perform a laparoscopy. This is a simple procedure where a medical professional inserts a camera through a small incision in the stomach. A doctor can use this to assess how many lesions a person has and surgically remove them if necessary.

Although laparoscopy is a simple surgery, it comes with some risks. If a doctor removes lesions from an ovary, they can decrease the number of eggs a person has.

For people who are 35 or older, doctors may recommend a combination of the drug clomiphene with intrauterine insemination (IUI) instead of surgery.

During this treatment, a person takes clomiphene citrate to trigger ovulation. When they are ovulating, a doctor will place sperm into the uterus with a thin tube.

If this treatment is unsuccessful, a doctor may suggest injectable fertility medications or IVF.

Treatments for stages III–IV

In the later stages of endometriosis, a doctor will likely recommend IVF.

This treatment requires a person to inject fertility medication that promotes egg growth. Once a person has enough eggs, a doctor harvests them. After selecting the best eggs, they fertilize each with sperm to create embryos.

The doctor then implants embryos into the uterus.

Endometriosis is a painful, progressive condition that can be difficult to cope with. People struggling to get pregnant with the condition may feel isolated and discouraged, especially if they have been trying for a number of years without success.

If someone needs additional resources, be it support groups or advice, they can try:

Endometriosis is a condition where endometrial-like tissue grows outside the uterus. It can impact a person’s fertility, making it harder to get pregnant.

People in the early stages of the disease may be able to conceive without medical assistance, but they are likely to need medication, IUI, or IVF in the later stages.

Living with endometriosis can be difficult, and support groups and resources can help those who are struggling.