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Endometriosis and the role of the womb lining in fertility

22 July 2020

We’ve been doing it since the dawn of time, but making babies remains a complicated and often mysterious endeavour for some. Multiple factors — including hormonal, environmental, physical and psychological — play their part. One key component of the physical variety is the endometrium, AKA the womb lining. Below is an introduction to its function in relation to fertility and some top-line information on endometriosis, a common condition that can affect a woman’s ability to conceive.  

What is the endometrium and how does it work? 

The endometrium is the lining of the womb, made up of a base layer and a functional layer, the latter of which changes under hormonal influence. At the start of a woman’s cycle, oestrogen is released and the endometrium grows to a thick layer of blood-vessel rich tissue, providing a perfect, cosy environment for the potential arrival and implantation of a fertilised egg.  

If pregnancy occurs, the lining further increases in size and thickness, eventually forming a placenta around the embryo. If pregnancy does not occur, the functional layer of the endometrium is shed and expelled through mensuration. Women who do not produce enough hormones to facilitate an optimal lining thickness (between 7mm and 14mm) may struggle to conceive. Such a problem can be detected via ultrasound and treated with oestrogen tablets. 

What is endometriosis?  

Endometriosis is a relatively common condition whereby tissue similar to that of the womb lining grows outside of the uterus, for example on the ovaries or bladder and in the fallopian tubes or bowel. It most commonly affects women of childbearing age who have a history of endometriosis in their immediate family. 

Endometriosis symptoms 

Endometriosis can be hard to detect, as while some women experience severe symptoms, others suffer very few or none at all. The severity of symptoms is also not connected to the severity of the condition. Some women experience severe symptoms with very mild endometriosis, while others with severe endometriosis have no symptoms. The most common symptoms include: 

  • Heavy, painful and irregular periods
  • Pain in the lower back, abdomen and pelvis, particularly during ovulation
  • Pain during and/or after sex
  • Pain when going to the toilet
  • Difficulty conceiving  

Endometriosis and fertility 

Some women with endometriosis find it harder to get pregnant, but around 7 in 10 with mild to moderate conditions conceive without the need for any treatment. While some women will experience intense pain throughout their lives and have to undergo multiple rounds of surgery, others only find out they have the condition when seeking medical help for infertility. 

Scientists are not yet clear about the exact nature of the link between endometriosis and infertility, although those with severe cases do seem to have more trouble conceiving. That said, it is still possible to get pregnant naturally when suffering from severe endometriosis.  

Treatment of endometriosis 

Treatments for endometriosis differ depending on the severity of the condition and the life plans of the patient. Hormonal treatments are commonly used for those not wanting to conceive, as such treatments, such as the contraceptive pill, mimic pregnancy. Women suffering from endometriosis who want to conceive can have surgery to remove the errant tissue if it is considered to be preventing conception. The most common surgical procedure for endometriosis is laparoscopy, minimally invasive keyhole surgery through a tiny incision by the belly button. 

If you either know or suspect you have endometriosis and are struggling to get pregnant, talk to your GP or gynaecologist. Both detection and treatment are relatively simple affairs, unlike conception itself!

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