Endometriosis and Fertility: What You Need to Know When Trying to Conceive

Endometriosis is one of the most common yet chronically underdiagnosed conditions affecting women of reproductive age. In Australia, it affects approximately 1 in 9 women — around 830,000 Australians — making it more common than diabetes. Despite this prevalence, women wait an average of 6.5 years from the onset of symptoms to diagnosis. For those trying to conceive, that delay can have real consequences.

The relationship between endometriosis and fertility is complex and often misunderstood. While endometriosis does increase the risk of fertility challenges, it does not mean that conception is impossible — not by a long way. Understanding the science behind how endometriosis affects reproduction, and what evidence-based options are available, is essential for anyone with this diagnosis who is hoping to start or grow a family.

How Endometriosis Affects Fertility

Endometriosis occurs when tissue similar to the endometrium (the lining of the uterus) grows outside the uterus — on the ovaries, fallopian tubes, peritoneal lining, bowel, and bladder. Like the uterine lining, this ectopic tissue responds to hormonal cycles — swelling, breaking down, and bleeding each month — but has no way to exit the body. Over time, this causes inflammation, scarring, and the formation of adhesions.

The mechanisms by which endometriosis impairs fertility are multiple and interconnected:

Anatomical distortion: Adhesions — bands of fibrous scar tissue — can cause the fallopian tubes to become blocked, kinked, or displaced, preventing the egg from traveling from the ovary to the uterus. Ovaries can become attached to surrounding structures (a "frozen pelvis" in severe cases), impairing the mechanical process of ovulation and egg pickup by the tube.

Inflammatory environment: The peritoneal fluid in women with endometriosis contains significantly elevated levels of inflammatory cytokines, activated macrophages, and prostaglandins. This toxic peritoneal environment can directly damage sperm, interfere with sperm-egg interaction, and impair implantation. Research has demonstrated reduced sperm motility when sperm are exposed to peritoneal fluid from women with endometriosis.

Endometrioma damage to ovarian reserve: Ovarian endometriomas (chocolate cysts) — fluid-filled ovarian cysts containing old menstrual blood — are particularly impactful on fertility. They are surrounded by ovarian cortex containing primordial follicles (the eggs in reserve). The inflammatory environment of the cyst, and the trauma of cyst formation and surgery, can both reduce the number of remaining eggs. AMH (anti-Müllerian hormone) levels are consistently lower in women with endometriomas compared to age-matched controls.

Reduced egg quality: Multiple studies have found evidence of reduced oocyte (egg) quality in women with endometriosis, independent of ovarian reserve. This is thought to result from the elevated oxidative stress environment, altered follicular fluid composition, and potential direct toxic effects of the endometrioma on surrounding follicles.

Implantation impairment: Endometriosis is associated with changes in the endometrial lining itself, including altered expression of implantation markers, reduced endometrial receptivity, and higher rates of uterine NK cell abnormalities. This can impair the embryo's ability to implant even after fertilization.

Altered immune response: Women with endometriosis show measurable differences in immune function, including elevated anti-endometrial antibodies that may create an immune environment hostile to conception and implantation.

Stages of Endometriosis and Fertility Outcomes

Endometriosis is classified by the American Society for Reproductive Medicine (ASRM) into four stages (I–IV) based on the location, extent, and depth of lesions, and the presence and severity of adhesions.

Stage I (Minimal): Small, isolated lesions without significant adhesions. Fertility impact is subtle — monthly fecundity (probability of conceiving in a given month) is estimated at 9.3% compared to approximately 20% in healthy fertile women, though many women with Stage I conceive without difficulty.

Stage II (Mild): More extensive superficial lesions with some adhesions. Monthly fecundity approximately 9.3%. The distinction between Stage I and II in terms of fertility outcomes is not always clinically significant.

Stage III (Moderate): Multiple deep implants and/or small endometriomas (typically <4 cm) with adhesions involving the tubes or ovaries. Fertility impact becomes more pronounced, with monthly fecundity estimates of approximately 5–6%. Surgical treatment is often recommended before attempting natural conception.

Stage IV (Severe): Large endometriomas (>4 cm), dense adhesions, and often significant anatomical distortion. Monthly fecundity rates drop to approximately 3–5%. IVF is often the first-line recommendation for Stage IV endometriosis, particularly in women over 35 or with reduced ovarian reserve.

It is important to note that stage does not perfectly predict fertility outcomes. Some women with Stage I or II have significant fertility challenges due to subtle inflammatory effects, while some women with Stage III or IV conceive naturally. Individualized assessment is essential.

Diagnosing Endometriosis

The historical gold standard for diagnosing endometriosis is laparoscopy — a minimally invasive surgical procedure in which a camera is inserted through the navel to visualize the pelvic cavity directly, with biopsies taken for histological confirmation. While laparoscopy remains the definitive diagnostic tool, earlier non-invasive approaches are increasingly available.

Symptoms: The classical symptoms of endometriosis include severe dysmenorrhea (painful periods, often debilitating), deep dyspareunia (pain with deep intercourse), chronic pelvic pain, and dyschezia (painful bowel movements during menstruation). However, many women with significant endometriosis have minimal or no pain — a fact that contributes to diagnostic delay. Conversely, period pain alone is not diagnostic.

Transvaginal ultrasound (TVUS): Skilled ultrasound operators can reliably detect ovarian endometriomas and deep infiltrating endometriosis involving the rectovaginal septum and bowel. The sensitivity of TVUS for detecting endometriomas exceeds 90%. However, superficial peritoneal endometriosis (Stage I–II) is not visible on ultrasound — so a normal ultrasound does not exclude endometriosis.

MRI: Pelvic MRI provides detailed characterization of deep infiltrating endometriosis, particularly for surgical planning. It does not reliably detect superficial lesions. Like ultrasound, it is a useful adjunct but not a substitute for laparoscopic diagnosis in many cases.

Biomarker tests: CA-125 is a serum marker that is elevated in some women with endometriosis but has poor sensitivity (around 50%) and specificity — it can be elevated in many other conditions. Newer biomarkers are under investigation, including microRNA panels, urinary biomarkers, and endometrial biopsy testing (including the ReceptivaDx test, which assesses BCL6 expression as a marker of endometrial inflammation associated with endometriosis).

Medical and Surgical Treatment Options

Treatment of endometriosis in the context of fertility requires careful balancing of two sometimes competing goals: reducing disease burden and preserving (or improving) ovarian reserve and pelvic anatomy.

Laparoscopic excision vs. ablation: Surgical removal of endometriosis can improve fertility outcomes, particularly for Stage I–III disease. A landmark Cochrane review found that laparoscopic surgery for minimal to mild endometriosis significantly increased cumulative pregnancy rates (odds ratio approximately 1.6) compared to diagnostic laparoscopy alone. Excision (cutting out lesions) is generally preferred over ablation (burning) for deep infiltrating disease, as it more completely removes the tissue.

Endometrioma surgery and the ovarian reserve dilemma: The decision to surgically remove ovarian endometriomas before IVF is one of the most contested areas of reproductive medicine. While large endometriomas (>4 cm) are generally recommended for surgical removal before IVF due to concerns about follicle access and infection, surgery itself invariably reduces ovarian reserve. The key question is whether the benefit of surgery (improved follicle access, better egg quality, reduced risk of cyst rupture) outweighs the cost (reduced AMH and antral follicle count). This decision must be individualized based on cyst size, bilateral vs. unilateral involvement, baseline ovarian reserve, and the surgeon's skill in ovarian conservation.

Hormonal suppression: GnRH agonists (e.g., Zoladex), combined oral contraceptives, the hormonal IUS, and progestogens are used to suppress endometriosis symptoms and disease progression. However, all hormonal treatments suppress ovulation and are not compatible with active trying to conceive. Their role in improving fertility outcomes when used before IVF is limited — a Cochrane review found no benefit of pretreatment hormonal suppression on IVF outcomes in women with endometriosis, with the possible exception of ultra-long GnRH agonist downregulation protocols.

GnRH agonist long protocol IVF: Some reproductive endocrinologists advocate for 3–6 months of GnRH agonist treatment immediately before IVF in women with severe endometriosis, based on evidence suggesting it may improve implantation rates. This remains an area of active research and clinical debate.

Natural Conception with Endometriosis: Statistics and Realistic Expectations

One of the most important things to understand about endometriosis and fertility is that conception — including natural conception — remains possible for many women. The statistics, while sobering, are not a sentence.

Population-level data suggests that 30–50% of women with endometriosis will experience fertility challenges. This means that 50–70% of women with endometriosis do conceive, including many who conceive naturally. Studies of women with untreated minimal to mild endometriosis who were trying to conceive naturally found cumulative pregnancy rates of 47% at 12 months and 72% at 2 years — lower than age-matched controls, but not negligible.

Factors that predict better natural conception outcomes with endometriosis include:

• Younger age (under 35)
• Stage I or II disease
• No prior ovarian surgery (preserved ovarian reserve)
• Short duration of infertility (less than 2 years)
• Normal semen analysis in the male partner
• Normal uterine anatomy on saline infusion sonography or hysteroscopy

The ESHRE (European Society of Human Reproduction and Embryology) guidelines recommend that for women with Stage I–II endometriosis who are under 35 with no other infertility factors, a period of expectant management (natural trying) of 12–24 months is reasonable before escalating to IUI or IVF. However, if ovarian reserve is borderline, or if the woman is over 35, earlier intervention is generally recommended.

Endometriosis and IVF: What the Research Shows

When natural conception is not occurring within an expected timeframe, IVF is a powerful option for women with endometriosis. However, the evidence suggests that IVF may be somewhat less successful in women with endometriosis compared to women with tubal factor infertility of similar age, for several reasons:

Ovarian response: Women with endometriosis — particularly those who have had previous ovarian surgery — often produce fewer eggs in response to stimulation (reduced ovarian reserve). Multiple studies have documented lower antral follicle counts and AMH levels in women with endometriosis, predicting lower egg yield per IVF cycle.

Egg quality: Several studies have found reduced fertilization rates and higher rates of embryo arrest in IVF cycles involving women with endometriosis, suggesting intrinsic egg quality issues that may relate to the oxidative stress environment of the endometriotic pelvis.

Implantation: Some research suggests reduced endometrial receptivity in women with endometriosis. The endometrial receptivity array (ERA), which tests for the personalized implantation window, may be beneficial in women with endometriosis and repeated implantation failure.

A large systematic review and meta-analysis (Hamdan et al.) found that women with endometriosis undergoing IVF had significantly lower clinical pregnancy rates per cycle (approximately 25–30%) compared to women with tubal factor alone (approximately 32–38%). However, cumulative success rates across multiple cycles remain favorable for many women with endometriosis, particularly when they have adequate ovarian reserve.

Lifestyle Approaches to Support Fertility with Endometriosis

While no lifestyle change reverses endometriosis, there is growing evidence that an anti-inflammatory approach can reduce disease activity, improve symptom burden, and potentially support fertility outcomes.

Anti-inflammatory diet: A Mediterranean-style diet — rich in omega-3 fatty acids (oily fish, walnuts, flaxseed), colorful vegetables, fruits, legumes, and extra-virgin olive oil — has been associated with lower endometriosis risk and reduced symptom severity. A prospective cohort study found that women with the highest intake of omega-3 fatty acids had a 22% lower risk of laparoscopically confirmed endometriosis. Conversely, high intake of trans fats was associated with a 48% increased risk.

Reduce pro-inflammatory foods: Processed foods, refined sugars, red and processed meats, and high-glycaemic carbohydrates promote systemic inflammation and may worsen endometriosis symptoms. Gluten and dairy are sometimes implicated anecdotally, though robust clinical evidence for elimination diets is limited.

Antioxidant supplementation: Vitamins C and E, N-acetylcysteine (NAC), and resveratrol have each shown preliminary evidence in small clinical trials for reducing endometriosis-related oxidative stress and potentially reducing cyst size. NAC (600 mg three times daily) was associated with reduced endometrioma size and improved fertility outcomes in a small Italian RCT. These findings require confirmation in larger trials but represent a low-risk adjunctive strategy.

Folate: Essential for all women trying to conceive, folate (as methylfolate for those with MTHFR variants) reduces the risk of neural tube defects and supports DNA replication — a particularly important consideration given the elevated oxidative stress environment of endometriosis.

Regular moderate exercise: Exercise reduces systemic inflammation, improves insulin sensitivity, and supports immune function. Moderate exercise is also a validated strategy for managing chronic pelvic pain. High-intensity exercise during painful flares is generally counterproductive.

Stress management: The bidirectional relationship between stress and inflammatory disease is well established. Mindfulness-based stress reduction (MBSR), yoga, and psychotherapy are all validated approaches for chronic pain management and may reduce the inflammatory burden that exacerbates endometriosis.

Frequently Asked Questions

Does endometriosis always cause infertility?

No. While endometriosis increases the risk of fertility challenges — affecting approximately 30–50% of women with the condition — the majority of women with endometriosis (50–70%) are able to conceive, including many who conceive naturally. The impact on fertility varies significantly based on disease stage, location, and individual factors.

Can I get pregnant naturally with endometriosis?

Yes. Many women with endometriosis conceive naturally, particularly those with Stage I or II disease, younger age, and no other fertility factors. Studies show cumulative natural conception rates of up to 72% at 2 years in women with untreated minimal to mild endometriosis. However, if you have been trying without success for 6–12 months, early evaluation with a reproductive specialist is recommended.

Should I have surgery before trying to conceive with endometriosis?

This depends on your individual situation — specifically your stage of disease, ovarian reserve, age, and how long you have been trying. For Stage I–II endometriosis, laparoscopic surgery has been shown to improve natural conception rates. For ovarian endometriomas, the decision to operate must carefully weigh the risk of surgical damage to ovarian reserve against the potential benefit. This decision should be made with a specialist experienced in fertility-preserving endometriosis surgery.

Does endometriosis worsen over time?

Endometriosis can progress, remain stable, or even regress over time — the trajectory is unpredictable and varies between individuals. Hormonal suppression slows progression but does not eradicate disease. Post-surgical recurrence rates range from 20–40% at 5 years. This unpredictability underscores the importance of not delaying fertility treatment unnecessarily.

Does IVF work well for endometriosis?

IVF is effective for women with endometriosis, though success rates are somewhat lower than in women with tubal factor infertility of similar age. Lower ovarian reserve and potential egg quality issues reduce average egg yield and fertilization rates. However, many women with endometriosis achieve successful pregnancies through IVF, particularly when ovarian reserve is preserved and embryo quality is good.

Can endometriosis come back after surgery?

Yes. Recurrence rates after laparoscopic surgery range from approximately 20–40% at 5 years, depending on the completeness of excision and the degree of disease at the time of surgery. More complete excision (rather than ablation) reduces recurrence risk. Many gynecologists recommend hormonal suppression after surgery in women not immediately trying to conceive, to slow recurrence.

Does diet help endometriosis?

A Mediterranean-style anti-inflammatory diet is associated with reduced endometriosis risk and symptom severity in observational studies. While diet cannot reverse established endometriosis, reducing intake of pro-inflammatory foods and increasing omega-3 fatty acids, antioxidants, and colorful vegetables is a reasonable, low-risk complementary strategy supported by the available evidence.

Does endometriosis cause miscarriage?

Women with endometriosis have a modestly elevated risk of miscarriage compared to women without the condition. This may relate to implantation defects, altered immune environment, or reduced embryo quality. The absolute risk increase is modest — most studies report miscarriage rates of 25–35% in women with endometriosis undergoing IVF vs. 15–20% in general IVF populations. Preimplantation genetic testing (PGT-A) may reduce this risk by selecting chromosomally normal embryos.

Is endometriosis hereditary?

There is a significant genetic component to endometriosis. First-degree relatives (mothers, sisters, daughters) of women with endometriosis have approximately a 7–10x higher risk of developing the condition compared to the general population. Multiple genomic studies have identified specific genetic variants associated with endometriosis risk, though no single "endometriosis gene" has been identified.

Can endometriosis be cured?

Currently, there is no cure for endometriosis. Treatments manage symptoms and reduce disease burden but do not eradicate the condition. Menopause typically (though not always) leads to regression of disease due to loss of estrogen stimulation. Research into disease-modifying treatments — including immune modulation, anti-angiogenic therapies, and targeted hormonal approaches — is an active area of investigation.