Endometriosis and Getting Pregnant

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Getting pregnant with endometriosis

Interpreting results
– Non-fertility based
– Fertility based

Updated: 23-August-2022


Getting pregnant with endometriosis is a step-by-step process. The first step towards effective treatment is diagnosing the type of endometriosis, its severity (stage) and any potential comorbidities.

Endometriosis is a common yet complex gynaecological inflammatory disease characterised by the growth of endometrial-like tissue outside the uterus (endometrium). As a chronic inflammatory disease, it is also found more often in women with other inflammatory diseases (interstitial cystitis, pelvic inflammatory disorder, irritable bowel syndrome).

Globally endometriosis affects around 190 million women worldwide, impairing quality of life both physically and mentally. These women, including some adolescents, are predominantly of reproductive age, of which 30 to 40% will suffer from infertility and or chronic pelvic pain.
Source: O’Hara R, et al. (2020); Zondervan K T. (2020); Howard F, (2009)

Male partners can have a positive effect on the psychological health and symptoms of pain in their partner, simply by taking a interest in their condition, and accompanying them to appointments.
Source: Facchin F, et al. (2021)

Common locations for endometriotic lesions include;

  • Ovaries
  • Uterine ligaments
  • Pouch of Douglas
  • Bladder wall
  • Bowel serosa
  • Fallopian tube mucosa
  • Myometrium

Endometriosis is classified into 3 subtypes, based on location and histopathology examination;

Superficial endometriosis

  • Occurs on the uppermost layer of soft tissues of the peritoneum or internal organs

Deep infiltrating endometriosis

  • Invades the muscular muscles of the organs

Ovarian endometriotic cysts (also known as endometriomas / chocolate cysts)

  • Attached to the ovaries

The size and location of these, along with any adhesions, determines the severity of endometriosis according to the rASRM (revised American Society for Reproductive Medicine), which is the most common classification system for endometriosis.
Source: Canis M, et al. (1997)

The rASRM scoring system classifies endometriosis into 4 types;

Stage 1 – Minimal Endometriosis
Stage 2 – Mild Endometriosis
Stage 3 – Moderate Endometriosis
Stage 4 – Severe Endometriosis

However this scoring system has well known limitations, primarily poor predictive power of pregnancy following surgery, compared to alternative systems.

In fact the severity of pain or likelihood of infertility does not correlate with the rASRM classification of endometriosis

Source: Zondervan K T, et al. (2020)

To begin understanding endometriosis and find some common links, numerous epidemiology studies have been carried out. Interestingly women with short menstrual cycles, above average height and early menarche are at higher risk of endometriosis, whilst giving birth, smoking and higher BMI is associated with a lower risk of endometriosis. Genetically women with a family history of endometriosis are also at greater risk, with the condition found to be 9 times more likely in Asian women compared to European or American women.
Source: Kim H J, et al. (2021); Dai Y, et al. (2018); Sharfrir A L, et al. (2018); Parasar P, et al. (2017); Parazzini F, et al. (2017)

Factors associated with increased risk
– Low birth weight / Small for gestational age
– Earlier age of menarche
– Shorter menstrual cycle length
– Taller height
– Vitamin D deficiency
– Alcohol intake
– Caffeine intake
Factors associated with decreased risk
– Nulliparity
– Current oral contraceptive use
– Smoking
– Higher body mass index
– Regular exercise
– Fish and omega 3 fatty acids

Risk factors for Endometriosis

However whether these factors are a cause of endometriosis, or the consequence, is unknown.

The latest theory suggests that exposure to low testosterone levels during pregnancy may be the starting point of endometriosis. Short anogenital distance, a well-known marker for in utero hormone exposure, has been linked to endometriosis. This would explain the inflammation associated with endometriosis, as testosterone is generally an immune system suppressor and inhibitor of inflammation.

Exposure to low testosterone levels during pregnancy may be the starting point of endometriosis.

There is further evidence to support this theory with the onset of pain among women with endometriosis reported to begin during adolescence. This suggests the development of endometriosis begins early in a woman’s life. Interestingly studies to date show that pain and testosterone levels are related somewhat. Specifically, low levels of testosterone increase the sensitivity to pain, and can be programmed early on during development.

At the biological level inflammation caused by endometriosis lesions, increases interleukin-1β (IL-1β) which is a key participant in the bodies inflammatory response. This increase in IL-1β / macrophages leads to a subsequent increase in Nerve Growth Factor, netrin-1 and localised neurogenesis, whereby new neurons are formed to connect existing nerve fibres with endometriosis lesions, resulting in the sensation of pain.
Source: Ding S, et al. (2021); Peng et al. (2020); Radzinsky V, et al. (2020); Foster R, et al. (2019)

Recurrence of pain post surgery is linked to the activation of neurogenesis and reduction in apoptosis (programmed cell death).

Source: Radzinsky V, et al. (2020)

In rare cases the only visible evidence of endometriosis in women, may be the presence of a hidden (peritoneal retraction) pocket. In these women, this peritoneal defect is commonly associated with pelvic pain, dyspareunia and secondary dysmenorrhea. In one study histopathologic analysis of tissue samples from these pockets found endometriosis in 60% of cases, followed by endosalpingiosis (13%) and chronic inflammation (7%) with only 20% of pockets considered normal.
Source: Koninckx P R, et al. (2021); Carranco R C, et al. (2020); Ilnitsky S, et al. (2019); Khan K N, et al. (2014); Vilos G A, et al. (2002)

Overall the endometrium of women with endometriosis differs significantly compared to women without.

Increased inflammation, altered microbiome composition, resistance to progesterone and in situ estrogen production, is believed to affect embryo fertilization and or implantation.
Source: Jin L, et al. (2022); Ma L, et al. (2021); Lee S R, et al. (2021); Zondervan K T. (2020)

Whilst subtle Fallopian tube abnormalities found in 70.9% of women with endometriosis, hinders the transport of the oocyte and fertilisation.

Source: Zheng X, et al. (2021)

In fact, studies show women with endometriosis are significantly more likely to have blocked fallopian tubes. This finding is true even among infertile women diagnosed with and without endometriosis. Researchers note that the risk of blocked fallopian tubes is higher according to the severity of endometriosis. Especially among women with rASRM stage III or IV endometriosis.


The majority of women with endometriosis become pregnant naturally, however 30 to 40% of these women experience infertility. The fecundity (fertility) rate per month for women with endometriosis is significantly lower, between 2 to 10% depending on the severity, compared to a normal fecundity rate of 15 to 20%.

As long as there are no other factors (male or female) negatively impacting the chance the pregnancy, couples are recommended to try and conceive naturally first prior to seeking treatment.


The best age to get pregnant with endometriosis according to the Endometriosis Fertility Index scoring system is before 35 years of age.  Women between 35 and 40 years of age with endometriosis, have 1 point deducted in this scoring system, while woman older than 40 lose 2 points.

The decrease in fertility for woman with endometriosis, according to this scoring system, is actually comparable to the decrease in fertility among woman without any fertility related conditions.

Range of fertility rates among women worldwide according to age

In fact the Endometriosis Fertility Index recognizes this, with the severity of the condition, and associated dysfunction, having greater effect in its scoring system than age alone (50% vs 20%).

This seemingly null effect of aging on endometriosis is supported by other studies, which suggest the growth of endometriosis lesions almost stops entirely once a woman reaches adulthood (~24y.o).
Source: Koninckx P R, et al. (2021)

This also means any future preventative treatments, will most likely begin early on during adolescence.

Symptoms of Endometriosis

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