Endometriosis And Pregnancy

Overview 

Endometriosis is a chronic condition that affects around 10% (190 million) of people assigned female at birth (AFAB) who are of reproductive age globally. Whilst some people with this condition are able to conceive and carry to full term, many people AFAB have difficulty in conceiving.

Endometriosis is one of the main causes of infertility worldwide, with previous studies suggesting around 25-50% of infertile women have endometriosis. Currently, there is no cure and the exact cause is unknown. However, some medicines and surgical procedures can help alleviate symptoms and aid conception.^1,2 

What is endometriosis?

The endometrium refers to the tissue which lines the uterus (diagram below of the female reproductive system).(Source)

Endometriosis occurs when tissue similar to the endometrium grows outside the uterus. This misplaced tissue can be found in the:

• Ovaries
• Fallopian tubes
• The outer surface of the uterus

When the cells continue to grow, they can form what is known as endometrial implants. These displaced cells then stick to the other parts of the reproductive system organs and continue to grow with each menstrual cycle, forming scar tissues and cysts. In rare cases, it can even spread beyond the pelvic region. The disease can start as early as the first menstrual period, but can also begin at a later age, and symptoms can last until menopause. 

Other factors which can contribute to endometriosis include genetic predisposition (although there is no single gene that causes it) and hormonal imbalances. Endometriosis is characterised by chronic inflammation within the pelvic cavity, as endometrial implants bleed and release inflammatory molecules with each menstrual cycle.

Oestrogen has a role in the inflammatory process in endometriosis. An ongoing inflammatory response can damage surrounding tissues, and create a hostile environment for fertilisation and embryo implantation. Inflammation may also contribute to the formation of scar tissue (fibrosis and adhesions), further complicating fertility and pregnancy outcomes.

Oestrogen promotes the growth of endometrial tissue, while progesterone helps to regulate the menstrual cycle and maintain the uterine lining. Abnormal hormone levels may also contribute to the development and persistence of endometrial implants outside the uterus.⁶ 

Symptoms 

The most common symptom of endometriosis is pain in the pelvic area. The pain can be mild to debilitating, significantly affecting quality of life. Pain is usually more noticeable during menstruation, or during sex, but can also rise during urination and bowel movements.  

Endometriosis can cause irregular or heavy menstrual bleeding, as well as clots or spotting between periods. Some people may also experience shortened or prolonged menstrual cycles.

Other (less commonly occurring) symptoms associated with endometriosis are gastrointestinal issues, such as:

• Bloating
• Nausea
• Altered bowel movements (e.g., diarrhoea or constipation), particularly during menstruation

If there are endometrial implants around the bladder, people can have urinary symptoms like urgency or pain while urinating. Again these symptoms are more common during menstruation.

Patients with endometriosis have a higher risk of developing mental health conditions, such as anxiety and depression. This is because endometriosis can cause regular pain and significantly reduce your quality of life. 

Some people with endometriosis do not have any severe symptoms, but may only realise something is wrong if they have problems when trying to conceive.^2,3 

Diagnosis

Early diagnosis is vital, as it allows more time to try different treatment options, particularly if you are trying to conceive. The only way to definitively diagnose endometriosis is to identify the endometrial adhesions, which can be seen on ultrasound scans or surgical procedures.

Unfortunately, receiving a diagnosis can be challenging for many people with symptoms, particularly people who have normalised intense pain during menstruation, or if their symptoms can be attributed to some other condition. Many have to wait years before appropriately being diagnosed.⁵ 

Impact on pregnancy

Endometriosis can interfere with conception by affecting various aspects of reproductive function. Abnormalities within the pelvis, including the formation of endometrial implants (aka adhesions), cysts, and scar tissue may bind pelvic organs together, such as the uterus, ovaries, and fallopian tubes.

This leads to distortion or blockage of the reproductive tract. As a result, sperm may have difficulty reaching the egg for fertilisation, or the egg may be obstructed from travelling down the fallopian tube for implantation in the uterus.

Adhesions can disrupt the normal function of the ovaries, impairing ovulation, and reducing the chances of successful conception. Inflammation associated with endometriosis may also impair ovarian function making it more difficult to achieve fertilisation.⁶

Evidence of the impact of treated endometriosis during pregnancy is limited, but some studies have shown that, even after surgery, there is an increased risk of complications, such as:

• Preterm birth
• Miscarriage
• Low birth weight

However, other evidence has suggested that these complications in pregnancy are rare.⁶ 

Managing endometriosis 

As there is no cure for this chronic condition, treatment mainly focuses on tackling symptoms. Hormone therapy is usually the first line of treatment for endometriosis. It is worth mentioning that due to the variety of hormones involved in the menstrual cycle, prescribing one hormone will have downstream effects on the other hormones and the cycle overall. 

As mentioned in the second part of this article, oestrogen is responsible for the proliferation of the endometrium during ovulation. Oestrogen activity is counteracted by the presence of progesterone. Therefore, these hormones are the main targets of hormone therapy. The most used treatments include progesterone tablets or the combined oral contraceptive pill (oestrogen and progesterone). 

Another type of hormone control used for endometriosis is known as gonadotropin-releasing hormone agonists, which inhibit the ovaries from producing oestrogen and progesterone. There are also gonadotropin-releasing hormone antagonists, which inhibit the production of two other hormones that affect the release of oestrogen and progesterone, FSH (follicle-stimulating hormone) and LH (luteinising hormone). Aromatase inhibitors can also be prescribed, which stop an enzyme in the ovaries from producing oestrogen. 

Hormone therapy has been shown to reduce pain as compared to no treatment, or a placebo. However, this treatment does have potential side effects, such as changes in mood or acne. Painkillers, particularly NSAIDs (non-steroidal anti-inflammatory drugs), such as ibuprofen may be prescribed to alleviate pelvic pain and discomfort.^2,5

Surgical intervention is often considered the “gold standard” of endometriosis management.  Laparoscopic surgery, (aka keyhole surgery), can be performed to remove endothelial adhesions. Studies have shown it can be very effective for pain relief.

Cysts can also be drained and removed surgically; this can help with pain and heavy bleeding during menstruation. Fertility improvement following surgery has been reported in some cases too. Nevertheless, surgery is not a “permanent fix”, since the chronic nature of endometriosis causes the adhesions to recur after surgery. Additionally, some lesions cannot be safely removed if they are too close to other anatomical structures.⁴

Fertility management

In addition to surgery in select cases, there are other methods of improving the chances of conception. Which methods are chosen is a highly individualised decision dependent on each case. 

Intrauterine Insemination (IUI)

IUI involves the direct placement of sperm into the uterus around the time of ovulation. This treatment may be recommended for mild to moderate endometriosis-related infertility. IUI can also be given with medication such as clomiphene citrate or gonadotropins that can stimulate ovulation to increase the chances of fertilisation.¹

In vitro Fertilisation (IVF)

IVF consists of merging the sperm and the oocyte (developing egg) outside of the human body and then re-inserting it into the uterus. Since endometriosis can sometimes reduce the number of eggs, ovulation-stimulating medication is often given along with IVF to extract a viable number of oocytes. IVF can also be attempted after surgery.¹

Evidence on the success of IVF for endometriosis is difficult to interpret as there are many factors which can affect the result, which may not all be accounted for in studies. However, overall evidence concludes that endometriosis itself - especially in mild and moderate cases - does not influence the outcome of IVF. Even though this treatment is more complicated than IUI, it is generally more reliable with higher success rates.⁷

Summary

Endometriosis is a chronic disease that affects the female reproductive system. Currently, there is no cure for endometriosis and its exact cause is still unclear. During endometriosis, the cells lining the uterus (the endometrium) grow elsewhere in the reproductive system, known as endometrial implants or adhesions.

The most common symptom is pain (which can be very severe) in the pelvic area, especially during menstruation. Due to the excess tissue formation, the structure of the reproductive system is altered in many ways which can cause difficulty in conceiving and in some cases, infertility. There is no cure, but medicines can help improve fertility and regulate hormones.

Surgery can remove the endometrial implants, which helps with managing pain and can improve the chances of fertility. However, re-appearance of these tissues is common due to their chronic nature. Overall, the management of endometriosis is challenging and requires more research to improve the quality of life of millions of people AFAB.