Discover what causes endometriosis, what triggers flare-ups, and which myths to ignore. Learn the real medical theories, warning signs, and when to see a specialist.

Introduction

Endometriosis is one of those conditions that sounds simple on the surface but gets complicated fast the moment you start asking real questions. People want to know what causes it, why it hurts so much, and whether things like stress, birth control, abortion, or a C-section can play a role. The honest answer is that endometriosis is complex, common, and still not fully understood.

What Causes Endometriosis?

Endometriosis happens when tissue that behaves like the lining of the uterus grows outside the uterus, often on the ovaries, fallopian tubes, pelvic lining, or nearby organs. Doctors know a lot about how it acts, but not everything about why it starts in the first place. That is why the topic is still actively studied around the world.

The exact cause is still unknown

The honest medical answer is that there is no single proven cause of endometriosis. Researchers have identified several strong theories, but none explains every case on its own. In one person, genetics may play the biggest role. In another, hormonal sensitivity may be more important. In others, immune changes or cell-development patterns may be part of the picture.  WHO and the NHS both state that the cause has not yet been proven, even though the condition is well recognized and can seriously affect pain, fertility, and quality of life.

Why There Isn’t One Proven Cause?

One reason endometriosis remains difficult to explain is that every patient is different. Two women may have similar symptoms but develop the disease through different biological pathways.

Researchers also know that many proposed theories cannot explain every case. For example:

• Many women experience retrograde menstruation, but only some develop endometriosis.
• Some women develop endometriosis before their first menstrual period.
• Endometriosis has even been reported, although extremely rarely, in unusual locations outside the pelvis.

These observations suggest that endometriosis is a multifactorial disease, meaning several mechanisms likely work together rather than one single cause.

The leading medical theories

Most experts now work with a group of leading theories rather than one master explanation. The main ideas include some theories. These theories do not compete to the point of canceling each other out; they often overlap and may all be part of the same biological story.

Retrograde menstruation

Retrograde menstruation is the theory that some menstrual blood flows backward through the fallopian tubes into the pelvic cavity instead of leaving the body. That tissue may then implant and survive in places where it should not be. It is one of the most accepted ideas in endometriosis research, but it cannot explain every case, because many people have retrograde flow and never develop endometriosis.

Genetics and family history

Genetics and family history matter because endometriosis often appears more frequently in people who have close relatives with the condition. WHO notes that family history is associated with endometriosis, which strongly suggests inherited susceptibility plays a role. This does not mean the disease is directly “passed down” in a simple way, but it does mean your background may influence risk.

Immune system dysfunction

Immune system dysfunction is another major theory. If the body does not clear misplaced endometrial-like cells effectively, those cells may survive, attach, and continue causing inflammation. WHO specifically notes emerging research linking endometriosis with immune dysregulation, which helps explain why the disease can behave like a chronic inflammatory condition.

Hormonal and inflammatory factors

Hormones do not appear to cause endometriosis by themselves. Rather, estrogen fuels the growth and activity of existing endometriosis tissue, which is why the condition is described as estrogen-dependent in major clinical references. Inflammation also plays a central role, because inflammatory pathways can help lesions persist, invade, and remain painful over time.

Embryonic cell theory and stem cells

Embryonic cell theory and stem cell theory suggest that certain cells may be present from early development or may later transform into endometriosis tissue. StatPearls and recent reviews describe stem cells as possible drivers of lesion growth and persistence, while embryonic-remnant theories help explain why endometriosis can appear in unusual locations. These ideas are still being explored, but they are now taken seriously in modern research.

Coelomic metaplasia

Coelomic metaplasia is the idea that certain cells in the lining of the abdomen or pelvis can change, or “metaplastically transform,” into endometrial-like tissue. This theory is especially useful for explaining cases that do not fit the retrograde menstruation model neatly. It is not the only explanation, but it remains one of the main scientific frameworks for understanding how endometriosis may develop.

How Do You Get Endometriosis?

People often ask how you get endometriosis as if there were a single event or exposure that causes it. In reality, you usually do not get it from one thing. It develops over time through a mix of risk factors, biology, and possibly inherited susceptibility. That is why two people can look almost identical on paper and still have very different outcomes. 

Is Endometriosis Something You Can Catch?

No, endometriosis is not contagious. You cannot catch it from sex, shared toilets, physical contact, or close living with someone who has it. It develops inside the body through biological mechanisms that are still being studied, which is very different from an infection or transmitted illness.

Risk factors that may increase your chances

Several risk factors may increase the chance of developing endometriosis. 

These include:

• family history of the condition, 
• early onset of periods, 
• having periods more often,
• certain reproductive patterns. 

WHO and JAMA both note family history and menstrual patterns as relevant risk factors, while the disease itself remains multifactorial rather than predictable from one factor alone.

Who is most likely to develop endometriosis?

Endometriosis most commonly affects women during their reproductive years, typically between ages 20 and 40, although symptoms often begin during adolescence.

You may be more likely to develop endometriosis if you:

• Have severe menstrual pain
• Have infertility
• Have close relatives with the disease
• Experience chronic pelvic pain
• Have painful intercourse
• Experience bowel or bladder pain during periods

WHO notes that it can occur in women, transgender men, and non-binary individuals who menstruate. In clinical practice, these people are eventually evaluated by a specialist such as Dr. Lucas Minig’s team in Valencia.

Can Stress Cause Endometriosis?

No, stress doesn’t cause Endometriosis. Stress is often blamed for almost everything, so it is understandable that people ask whether it can cause endometriosis. The evidence does not support stress as the root cause, but it does show that stress and endometriosis interact in important ways, especially when symptoms become more difficult to manage.

What Research Shows

Research suggests that the relationship between stress and endometriosis is real, but not simple. Clinical studies show high levels of chronic stress in people with endometriosis, and reviews indicate that stress may affect symptom burden, pain perception, and overall coping. That is very different from saying stress causes the disease in the first place.

How stress can worsen symptoms and pain?

Stress can make pain feel louder, heavier, and harder to ignore. It can also amplify the body’s inflammatory response and make the nervous system more sensitive to discomfort. So while stress does not create endometriosis out of nowhere, it can turn an already hard day into a full-blown flare-up.

What Causes Endometriosis Flare-Ups?

Endometriosis flare-ups are often the part patients remember most because they arrive like a storm: suddenly, intensely, and with symptoms that feel bigger than the day before. The triggers can differ from person to person, but a few patterns keep showing up across research and patient experience.

Hormonal fluctuations

Hormonal fluctuations are one of the biggest flare-up drivers. Because endometriosis is estrogen-sensitive, symptoms often intensify around the menstrual cycle when hormones shift. That is why many patients notice a predictable monthly pattern, even if the pain itself can be unpredictable.

Inflammation

Inflammation can make a flare-up feel more aggressive and more widespread. Endometriosis creates inflammatory activity in the pelvic environment, and that inflammation can increase pain, swelling, tenderness, and fatigue. This is one reason endometriosis is now widely described as an inflammatory disease rather than just a “bad period” condition.

Diet and lifestyle triggers

Diet and lifestyle do not cause endometriosis, but they can influence how a flare feels. Some people notice that certain foods, alcohol, gut irritation, or a very sedentary routine make symptoms harder to tolerate. The impact is individual, so the same meal or habit may bother one patient and not affect another at all.

Lack of sleep and chronic stress

Lack of sleep and chronic stress often work together like a double punch. Poor sleep lowers resilience, increases pain sensitivity, and makes inflammation harder to manage, while ongoing stress keeps the nervous system on alert. Together, they can make endometriosis flares feel longer, sharper, and more exhausting.

Why Flare-Ups Differ From Person to Person?

Flare-ups differ because endometriosis itself is different from person to person. Some patients have deep pain, some have bowel symptoms, some have urinary pain, some have infertility, and some have all of the above. That variability is exactly why a specialist evaluation matters, especially when symptoms interfere with normal life or fertility goals.

Can an Abortion Cause Endometriosis?

This is one of the most sensitive myths around the topic, and it deserves a careful answer. People often search this after hearing conflicting advice online, but medical evidence does not support abortion as a cause of endometriosis.

What research actually shows?

A 2025 Mendelian randomization study found no statistically significant causal association between different types of abortion and endometriosis, and no significant causal effect in the reverse direction either. That means the study did not support the idea that abortion causes endometriosis.

Separating myths from medical evidence

The confusion usually comes from mixing up association with causation. Some studies may look at people with endometriosis and abortions in the same dataset, but that does not prove one caused the other. The better-supported explanation is that endometriosis is influenced by genetics, hormones, immunity, and anatomy—not by a past abortion.

Can a C-Section Cause Endometriosis?

A C-section does not usually cause pelvic endometriosis, but a rare type called scar endometriosis can develop in the surgical incision. This is a real condition, and it is one reason patients with a painful lump near a C-section scar should be evaluated rather than dismissed.

Understanding scar endometriosis

Scar endometriosis happens when endometrial-like tissue appears in or near a surgical scar, most often after a cesarean delivery. Patients may notice pain, swelling, or a lump that becomes more noticeable during their menstrual cycle. It is uncommon, but it is well documented in the medical literature.

How common is cesarean scar endometriosis?

Cesarean scar endometriosis is rare. Published sources report approximate incidence ranges such as 0.03% to 0.4% of cases in some reviews, which is low enough to be uncommon but high enough that doctors should know to look for it when symptoms fit.

The Difference Between Pelvic Endometriosis and Scar Endometriosis

Pelvic endometriosis usually involves the ovaries, fallopian tubes, pelvic lining, bowel, or bladder. Scar endometriosis, by contrast, develops in the abdominal wall or scar tissue from surgery. They are related conditions, but they are not the same thing, and they may present with different symptoms and treatment plans.

Does Birth Control Cause Endometriosis?

Birth control does not cause endometriosis. In fact, hormonal contraceptives are commonly used to help manage symptoms because they can reduce ovulation, calm hormonal cycling, and lower pain for many patients. That makes this myth especially important to clear up.

Why birth control does not cause the disease?

The disease process begins through biological mechanisms that are already in motion long before a person starts contraception. NHS guidance describes hormonal medicines, including the combined contraceptive pill, as treatment options for endometriosis symptoms, not as causes of the condition.

How hormonal contraceptives help manage symptoms?

Hormonal contraceptives may reduce pain by suppressing the hormonal peaks that feed endometriosis activity. WHO and the NHS both note that hormonal treatment can help manage symptoms, even though it is not a cure. For many patients, this can feel like turning down the volume rather than switching the disease off completely.

Can Endometriosis Grow While on Birth Control?

Yes, it can still progress or remain active in some people while they are on birth control. That is because hormonal suppression often helps control symptoms, but it does not always eliminate existing lesions. Some patients improve a lot, some improve partially, and some need further specialist treatment.

When to See a Specialist?

Not all pelvic pain is endometriosis, but persistent pain, heavy bleeding, fertility issues, and bowel or bladder symptoms should not be brushed aside. If symptoms are affecting daily life, work, relationships, or pregnancy plans, that is the moment to move beyond guessing and get a specialist opinion.

Symptoms that should not be ignored

The most common symptoms of endometriosis that shouldn’t be ignored are: 

• Severe period pain, 
• Pain during sex, 
• Pain when you poo or pee, 
• Chronic pelvic pain, 
• Heavy bleeding, 
• Fatigue, 
• Difficulty getting pregnant 

These symptoms are all red flags that deserve attention. WHO and the NHS both stress that symptoms can vary widely and that diagnosis is often delayed, which is exactly why early evaluation matters.

Why expert care matters?

Expert care matters because endometriosis is often underdiagnosed, under-treated, and misunderstood. A specialist can help confirm what is going on, choose the right tests, and decide whether medications for endometriosis, surgery, fertility support, or a combination approach makes sense. That is especially important when symptoms are severe or when conservative care is not enough.

How Dr. Lucas Minig’s Team Helps Patients?

Dr. Lucas Minig’s practice is built for patients who need more than a rushed appointment and a generic pain prescription. The site highlights video consultations, international patient support, and individualized treatment in Valencia, which is a practical fit for people who want expert care without the usual waiting-list drag.

Video consultations and international patient support

For patients traveling from abroad or managing symptoms from a distance, video consultation is a real advantage. Dr. Lucas Minig explicitly offers online consultation and welcomes international patients, which makes it easier to review symptoms, discuss fertility goals, and plan next steps before travel or treatment.

Minimally invasive laparoscopic and robotic treatment

The practice also emphasizes minimally invasive laparoscopic and robotic surgery, with over 95% of complex procedures performed that way according to the site. For endometriosis patients, that matters because smaller incisions, less tissue disruption, and faster recovery can make a huge difference in the real world, not just on paper.

FAQs

Can endometriosis be prevented?

At present, there is no known way to fully prevent endometriosis. WHO notes that early awareness, early diagnosis of endometriosis, and quality care may help slow progression and reduce long-term impact, but there is no guaranteed prevention strategy.

Does endometriosis always cause infertility?

No, not always. Endometriosis can make it harder to get pregnant, and WHO notes a strong link between the condition and infertility, but many people with endometriosis do conceive, sometimes with treatment or fertility support.

Can teenagers get endometriosis?

Yes, endometriosis can begin in adolescence, sometimes with very painful periods.

Can endometriosis be cured?

There is no universal cure, but many patients can manage symptoms well with medication, hormonal therapy for endometriosis, or surgery.

Can endometriosis grow while on birth control?

Yes, symptoms can still continue or progress while using birth control. Hormonal contraceptives may reduce pain and bleeding, but they do not always stop every lesion from growing.

Conclusion

So, what causes endometriosis? The most accurate answer is that no single cause has been proven. Instead, the condition appears to involve a mix of retrograde menstruation, genetics, immune dysfunction, estrogen sensitivity, inflammation, and in some cases rare scar-related mechanisms. Stress can worsen symptoms, birth control does not cause endometriosis, abortion is not supported as a cause, and a C-section can rarely be linked to scar endometriosis rather than pelvic disease.

That is why endometriosis deserves specialist attention, not guesswork. If symptoms are affecting your life, a focused evaluation with an experienced gynecologist can help separate myths from facts and move you toward the right treatment plan. Dr. Lucas Minig’s Valencia team is positioned exactly for that kind of care, especially when minimally invasive treatment and international access matter.