Infertility
Endometriosis and infertility
Pain, ovarian reserve and pregnancy: a decision that needs a careful approach
Endometriosis affects about 10-15% of women of reproductive age and is found in a large share of women who struggle to get pregnant. About 25% of IVF cycles are carried out in women with endometriosis. It is often diagnosed only when pregnancy is delayed, even though period pain has been present for years. More about the disease in the article “Endometriosis”.
The link between endometriosis and fertility is complex. The disease does not act only through adhesions on the tubes and ovaries, but also through inflammation in the abdomen, through the immune system, through egg quality and through the lining of the uterus. A 2025 review in the Archives of Gynecology and Obstetrics summarizes the current state of knowledge, based on the 2022 guideline of the European Society of Human Reproduction and Embryology (ESHRE). This article is based on that review.
Which forms and classifications exist?
Endometriosis has three main forms: superficial endometriosis on the peritoneum, cysts on the ovaries (endometriomas) and deep infiltrating endometriosis, in which the lesions grow more than 5 millimeters deep into the tissue. The best-known classification is that of the American Society for Reproductive Medicine (rASRM), with four stages. It describes the extent and location of the disease, but it predicts fertility poorly. The Enzian classification describes deep lesions in more detail.
To estimate fertility after surgery, doctors use the Endometriosis Fertility Index (EFI). It takes into account age, the duration of infertility, previous pregnancies, the function of the tubes and ovaries and the stage of the disease. A score above 7 points to a good chance of a natural pregnancy after surgery. A lower score favors IVF. ESHRE sees the EFI as a reliable, simple and low-cost tool for this decision. The partner's semen analysis is always part of the decision.
Why does endometriosis affect fertility?
Anatomy. Adhesions can restrict the movement of the ovaries and disturb the pick-up and transport of the egg through the tube. Pain during intercourse also often reduces how often a couple has sex, and hormonal treatment for pain also prevents pregnancy.
Inflammation. The abdominal cavity of women with endometriosis contains more inflammatory substances, prostaglandins, free radicals and activated macrophages. This environment harms sperm and their DNA. It also affects fertilization and the quality of eggs and embryos.
The immune system. Certain immune cells function abnormally, and the body does not adequately clear cells of the uterine lining that lie outside the uterus.
The lining of the uterus. The lining in women with endometriosis responds less well to progesterone and is more strongly influenced by estrogen. Some factors that are important for embryo implantation are present at lower levels, and the lining is more inflamed. The authors of the review see this altered uterine environment as at least as important as anatomy.
Ovulation. The data on ovulation are conflicting. A larger study with almost 1,200 cycles found no difference in ovulation between the ovary with endometriosis and the ovary without it. Raised prolactin, a follicle that does not rupture and a disturbed luteal phase may, however, play a role.
How do endometriomas affect ovarian reserve?
Endometriomas reduce the number of small follicles on ultrasound and the AMH. Large and bilateral cysts can reduce the response of the ovaries to stimulation during IVF. Even so, surgical removal of the cysts before an IVF stimulation cycle is not always necessary, and it can reduce the ovarian reserve even further. Each woman makes this decision individually, after she has been fully informed. Pregnancy and live birth rates, however, do not appear to be worse. The damage comes mainly from the iron in the cyst fluid, which leads to oxidative stress, scarring and faster depletion of the ovarian reserve. Women with endometriomas, especially women who have not given birth and do not take the pill, have a higher risk of early menopause. More in the article “Diminished ovarian reserve”.
What happens to egg and embryo quality?
In IVF, women with endometriomas produce fewer mature eggs. According to large reviews, however, fertilization and the share of good-quality embryos are similar to other women. Other studies show changes in embryo development. Studies with donated eggs show lower implantation rates when the donor has endometriosis. This suggests that the disease also affects the egg itself.
Why does diagnosis come before treatment?
The most important tests are vaginal ultrasound and MRI. With standardized examination protocols, deep lesions, endometriomas and adhesions can be identified reliably. Superficial endometriosis on the peritoneum is often not visible on ultrasound or MRI. A laparoscopy with a tissue sample is needed to diagnose it with certainty. A laparoscopy only for diagnosis before IVF, however, is not recommended.
The authors of the review stress that an accurate picture of the disease before treatment matters not only for planning surgery, but also for choosing the fertility treatment. In everyday care, however, IVF often starts without this assessment.
What does adenomyosis mean for fertility?
In adenomyosis, tissue of the uterine lining grows into the muscle wall of the uterus. In the past, adenomyosis was seen as a form of endometriosis. Today it appears to be a separate condition, although the two diseases often occur together. On MRI, a thickness of the inner muscle layer (junctional zone) of more than 12 millimeters supports the diagnosis. Besides MRI, many signs on transvaginal ultrasound help with the diagnosis. International criteria (MUSA) describe these signs in a uniform way: an unevenly thick uterine wall, small cysts and bright islands in the muscle wall, fan-shaped shadows and a blurred or interrupted junctional zone. In many women, the final diagnosis and treatment come only with a hysterectomy.
Adenomyosis lowers the pregnancy rate by 31-43%. After IVF, the risk of miscarriage is about three times higher, and the live birth rate is about 55% lower. According to a 2025 review, diffuse adenomyosis is also linked to more preterm births, growth problems of the baby, placental problems, cesarean sections and bleeding after birth.
What can medication do?
The pill, progestins, the hormonal IUD and medicines that strongly lower estrogen suppress ovulation and the activity of the lesions. They relieve pain, but at the same time they prevent pregnancy. ESHRE does not recommend hormonal suppression to improve natural fertility, nor hormonal treatment after surgery with the sole aim of pregnancy. For women who do not want to become pregnant at the moment, however, hormonal treatment is a good option. AMH can be about 25% lower while taking hormonal contraception, but it rises again after stopping.
When does surgery help a natural pregnancy?
Superficial endometriosis. According to a Cochrane review, removing the lesions during laparoscopy increases the chance of a natural pregnancy compared with a laparoscopy for diagnosis only. ESHRE recommends surgery in women with symptoms and stage I or II, as a weak recommendation.
Endometriomas. Removing cysts larger than 3 centimeters improves the chance of a natural pregnancy more than draining or vaporizing the cyst. It does, however, reduce the ovarian reserve and can cause adhesions. According to ESHRE, surgery is an option, but not routine for fertility.
Deep infiltrating endometriosis. After surgery, 24-44% of women become pregnant naturally. Most of these studies, however, have no comparison group. Radical surgery carries risks. Because of the high rate of recurrence, the trend is toward a cautious and individual approach. According to ESHRE, surgery for deep endometriosis serves mainly to treat pain and may not improve natural fertility.
The decision takes into account pain, age, the woman's wishes, previous surgery, other causes of infertility, ovarian reserve and the EFI.
When is insemination an option?
Insemination (IUI) is a step between waiting and IVF. ESHRE suggests insemination with ovarian stimulation as the first choice in stage I or II, with a good ovarian reserve, open tubes and no significant male factor. According to the review, this applies especially to women under 35. In stage III or IV, insemination is not recommended.
What does IVF offer?
IVF is the most effective treatment, because it bypasses the tubes and the environment in the abdomen. Older data showed worse results in endometriosis. Newer large registry data from Norway, however, showed similar live birth rates to other women (66.0% versus 66.7%), and the American data from 2022 also showed no significant difference. ESHRE prefers IVF in stage III or IV, with impaired tubal function, a low EFI and after repeated unsuccessful treatments.
Advanced stages reduce implantation and the pregnancy rate. Endometriomas reduce the ovarian response and increase the need for hormones, but they usually do not worsen embryo quality or the live birth rate. Deep infiltrating endometriosis is a stronger sign of poorer results: in one study the pregnancy rate was 58%, compared with 83% in superficial endometriosis.
No stimulation protocol is clearly better. The long protocol with a GnRH agonist gives more eggs, the protocol with a GnRH antagonist is shorter and less burdensome, and pregnancy and live birth rates are similar. ESHRE strongly advises against long pretreatment with a GnRH agonist before IVF, because it does not increase the live birth rate.
The concern that stimulation makes endometriosis worse is usually not confirmed. In one study, 77% of women had fewer symptoms three to six months after IVF, 11% had more, and the size of the endometriomas stayed the same. In stage III or IV, the recurrence rate after IVF was even lower than after inseminations.
Which path fits which stage?
Stage I or II
Stage III or IV
Does surgery help before IVF?
ESHRE strongly advises against routine surgery before IVF in stage I or II or with endometriomas. It does not improve the live birth rate and can reduce the ovarian reserve. Surgery for endometriomas can be considered for pain or when the cyst blocks access to the follicles during egg collection. In deep endometriosis, the decision depends on pain and the woman's wishes. Surgery for deep endometriosis only to improve IVF is not recommended, because complications are not rare: about 2% during and 14% after surgery.
Accepted reasons for surgery before IVF are a fluid-filled tube (hydrosalpinx), pain, a rapidly growing endometrioma and lesions that block egg collection.
When does egg freezing make sense?
In endometriosis, freezing eggs is a way to preserve fertility, especially before surgery on the ovaries and in younger women with a still good ovarian reserve. In a large study, the cumulative live birth rate after egg freezing was 61.9% in women up to 35 and 28.4% in women over 35. The greatest benefit is expected with bilateral endometriomas and before repeat surgery. When stimulation is not possible, freezing ovarian tissue can be considered.
What do the numbers show for endometriosis?
Birth rate with IVF, Norway
Pregnancy rate with IVF
Births after egg freezing
What about mental strain and quality of life?
Women with endometriosis who want a child carry a double burden: the pain and the uncertainty about pregnancy. They often have to choose between a treatment that relieves the pain but prevents pregnancy, and trying for a pregnancy while in pain. This is why ESHRE sees psychosocial support as part of fertility treatment. Without it, many couples stop treatment earlier than they should. Clear information, a plan with concrete steps and treating the pain alongside the attempt to conceive reduce this burden.
The practice's approach
With endometriosis and a wish for a child, the practice follows a plan that protects both the ovaries and the time available. The doctor weighs every decision on surgery, insemination or IVF according to the ESHRE guidelines and on the basis of the woman's full hormonal and reproductive profile.
Sources: Elizur SE, Mostafa J, Berkowitz E et al., Orvieto R. Endometriosis and infertility: pathophysiology, treatment strategies, and reproductive outcomes. Archives of Gynecology and Obstetrics 2025. ESHRE – Guideline Endometriosis (2022). Adamson GD, Pasta DJ – Endometriosis Fertility Index (EFI), Fertility and Sterility 2010. Bafort C et al., Cochrane Database of Systematic Reviews 2020 (surgery for endometriosis and infertility). Cobo A et al., 2020 (egg freezing in endometriosis). Gameiro S et al., ESHRE guideline: routine psychosocial care in infertility and medically assisted reproduction, Human Reproduction 2015. Gameiro S et al., Why do patients discontinue fertility treatment? A systematic review of reasons and predictors of discontinuation, Human Reproduction Update 2012. Harmsen MJ, Van den Bosch T, de Leeuw RA et al. Consensus on revised definitions of Morphological Uterus Sonographic Assessment (MUSA) features of adenomyosis: results of modified Delphi procedure. Ultrasound in Obstetrics & Gynecology 2022.