Endometriosis and Fertility: What You Need to Know
I talk about endometriosis every day, and I want to share what you need to know if you have endometriosis or unexplained infertility. Endometriosis is underdiagnosed because it presents differently in every person, and its impact on fertility can vary widely. Let’s break it down.
What is Endometriosis?
Endometriosis is the presence of glands and stroma, which are like the endometrial layer of the uterus, in places outside the uterus. The endometrium is the innermost layer of the uterus that sheds during your period. It grows in response to estrogen and compacts with progesterone.
When endometrial-like tissue implants elsewhere—on the uterus, fallopian tubes, ovaries, behind the uterus, intestines, liver, diaphragm—it triggers an inflammatory response. Your body sees these implants as abnormal, sending immune cells to attack them, which leads to inflammation and, over time, scar tissue formation.
Endometriosis is staged based on the amount of disease seen during surgery, from Stage 1 (mild) to Stage 4 (severe).
Endometriosis as an Inflammatory Disease
I like to think of endometriosis as an inflammatory disease. Chronic inflammation can create a toxic environment in the pelvis and disrupt anatomy, sometimes destroying tissue planes.
About 1 in 10 reproductive-age women has endometriosis.
Among women with infertility, 25–50% have endometriosis.
About 30–50% of women with endometriosis will experience infertility.
Many patients categorized as having “unexplained infertility” may actually have undiagnosed endometriosis because the gold standard for diagnosis is surgical visualization and biopsy. Not everyone undergoes surgery, and often it isn’t even recommended initially.
Endometriomas and Ovarian Reserve
In Stage 4 endometriosis, a special type of cyst called an endometrioma can form on the ovary. These cysts:
Are endometriosis tissue trapped inside a growing follicle.
Thrive due to the ovary’s rich blood supply.
Can decrease ovarian reserve, affecting fertility more than regular ovarian cysts.
Even without an endometrioma, endometriosis can cause a faster decline in ovarian reserve due to chronic inflammation. Surgery can help, but removing endometriomas also causes some residual ovarian damage, so the decision to operate must be carefully considered.
Endometriosis and Fertility Odds
Endometriosis reduces your monthly chance of getting pregnant:
Under age 35, natural monthly fecundability is 15–20% in women without endometriosis.
With endometriosis, it drops to 2–10% per month.
Pregnancy rates vary by stage:
Mild (Stage 1–2): ~50% conceive naturally.
Moderate (Stage 3): ~25% conceive.
Severe (Stage 4): Few conceive without intervention.
Surgery can improve pregnancy rates, but even then, only about 47% conceived within three years after excision.
Fertility Treatment Options
Ovulation Induction + IUI
Often first-line for mild endometriosis or unexplained infertility.
Success rates are lower in endometriosis compared to unexplained infertility alone (~8% chance per month).
Factors to consider: age, ovarian reserve, number of children desired, and time to pregnancy.
IVF
Recommended for severe endometriosis (Stage 3–4).
Surgery does not improve IVF outcomes in most cases.
Repeat ovarian surgeries worsen outcomes, so secondary surgery should focus on pain management, not fertility.
Special Considerations for IVF
Recurrent implantation failure may be linked to endometriosis.
Lupron protocols (GnRH agonists) before or during embryo transfer can improve pregnancy and live birth rates in some patients.
For unexplained infertility or mild endometriosis, standard embryo transfer protocols may be sufficient.
Studies show that patients with endometriosis can achieve similar live birth rates to those without, especially with euploid embryo transfers and appropriate protocols.
Symptoms and Advocacy
Classic symptoms of endometriosis include:
Painful periods
Pain with intercourse
Gastrointestinal changes during menstruation
However, many women are asymptomatic, and infertility may be the only symptom. Endometriosis is also more common in women with autoimmune conditions, such as thyroid disease.
Advocate for yourself:
Ask questions about your fertility options.
Consider egg freezing if diagnosed young but not ready for pregnancy.
Discuss timing and treatment strategies with your doctor.
Take-Home Message
Endometriosis is complex and impacts fertility in multiple ways. If you have infertility or unexplained fertility issues, consider the possibility of endometriosis and strategically plan your fertility treatment.
Your goals, age, ovarian reserve, and stage of disease are key factors in choosing the best approach—whether that’s surgery, IUI, or IVF.
