by Ros Wood

Little research has been carried out when it comes to endometriosis and fertility …but, overall it is generally “felt” that women with endometriosis may have a harder time becoming pregnant.

Studies indicate that women with minimal–mild endometriosis take longer to conceive (become pregnant) and are less likely to conceive than women in general.

It also appears that the more severe the woman’s endometriosis, the more likely it is that she will have difficulty becoming pregnant. Thus, women with moderate–severe endometriosis tend to have more difficulty conceiving than women with minimal–mild endometriosis.

Endometriosis does not equal infertility!

It is important to remember that having endometriosis does not automatically mean that you will never have children. Rather, it means that you may have more problems in getting pregnant.

Many women with endometriosis have children without difficulty, and many others become pregnant eventually — though it may take time, and may require the help of surgery or assisted reproductive technologies or both.

» Endometriosis and assisted reproductive technologies

In one Australian study involving 3895 women with endometriosis, 54% of the women who tried to become pregnant did not succeed in the first 12 months of trying. However, 70% of them ended up having at least one child [1]*. In comparison, in 1995, the incidence of infertility in US women was 10.2% [2].

* This study included women who tried to conceive in the 1970s and earlier when assisted reproductive technologies were not available or were less successful than today. Therefore, the figure of 70% may be an underestimate.


In most cases, it is not understood why it is harder for women with endometriosis to become pregnant.

The exception to the rule is when the woman’s endometriosis is severe enough to cause damage to one or more of the organs involved in conception. For example, if the ovaries are covered in thick adhesions, the egg may not be able to escape from the ovary to be fertilised. Similarly, if the ovaries or fallopian tubes are stuck in abnormal places by adhesions, the newly released egg may not be able to ‘find’ the entrance to the fallopian tube. Such damage is usually found only in some women with moderate or severe endometriosis [3].

Many theories have been proposed to explain why it is harder for women with endometriosis to conceive. However, as yet, none have been proven. It is possible that there are several causes and that different causes are relevant in different women. Some of the theories include:

  • pelvic adhesions inhibit the movement of the egg down the fallopian tube
  • eggs are of poor quality
  • chemicals produced by the endometriosis inhibit the movement of the egg down the fallopian tube
  • inflammation in the pelvis caused by endometriosis stimulates the production of cells that attack the sperm and shorten their life span
  • eggs are not released from the ovaries each month (also known as anovulation, which may also occur in women without endometriosis) [4].


There is no evidence that endometriosis causes women to have repeated miscarriages [5].

Also, there is no evidence that treating endometriosis results in women having fewer miscarriages [6, 7].

Hormonal treatment

Minimal–mild endometriosis
In women with minimal–mild endometriosis, hormonal drugs are not an effective treatment for endometriosis-related infertility, as none of the drugs leads to better pregnancy rates. Therefore, they should not be used to improve fertility in women with minimal–mild endometriosis [8].

Moderate–severe endometriosis
In women with more severe disease, no published studies have looked at the effect of hormonal treatment on infertility. However, it is assumed that they are not effective, so they should not be used to improve infertility in women with moderate–severe disease [9].

Surgical treatment

Surgery for endometriosis-related infertility aims to remove any endometriosis and adhesions present. If the endometriosis has damaged any organs, or resulted in them being stuck down in abnormal positions, the surgery will also try to repair the damage and restore the anatomy of the organs to as close as possible to their normal positioning [9].

Minimal–mild endometriosis
In women with minimal–mild endometriosis, laparoscopic surgery is an effective treatment for endometriosis-related infertility, as it leads to better pregnancy rates than a diagnostic laparoscopy alone [10].

Moderate–severe endometriosis
In women with moderate–severe endometriosis, no well designed studies have looked at the effect of surgery on pregnancy rates [9].

However, three studies seem to suggest that the more severe the endometriosis the lower the pregnancy rates following surgery [11, 12, 13]. In other words, it seems that women with severe endometriosis are less likely to become pregnant following surgery than women with mild or moderate endometriosis.

Nevertheless, some gynaecologists believe that women with the most severe forms of endometriosis have the greatest improvements in pregnancy rates following surgery [14]. In other words, surgery seems to increase their chances of becoming pregnant proportionally more than women with less severe endometriosis.

Ovarian endometriomas
There is considerable debate about how large ovarian endometriomas in women with endometriosis-related infertility should be treated [9]. The three main treatments are:

  • draining the endometrioma
  • draining and coagulating (burning the lining of) the endometrioma
  • excising (remove by cutting out) the endometrioma from the ovary.

Several studies indicate that laparoscopically excising large endometriomas greater than 4 cm in diameter leads to increased pregnancy rates and decreased recurrence rates compared with draining and coagulating the endometrioma [15, 16, 17, 18].

Removing an ovarian endometrioma allows the diagnosis of endometriosis to be confirmed by a pathologist, may reduce pain and discomfort, and may make it easier for the gynaecologist to collect follicles (potential eggs) for IVF [9].

However, removing an endometrioma may also result in the removal of some of the adjacent ovarian tissue, including some follicles (potential eggs). This may lead to decreased functioning of the ovary and occasionally even loss of ovarian function, particularly in women who have had previous ovarian surgeries [9].

Thus, the decision to remove or not remove an endometrioma must be carefully considered in the light of your circumstances [9].

  1. Treloar SA, Martin NG, Kennedy SH and Montgomery GW. Characteristics and symptoms in 3895 women diagnosed with endometriosis in an Australian genetic epidemiological study. World Endometriosis Congress 2005 presentation.
  2. Speroff L and Fritz M. Clinical gynecologic endocrinology and infertility. United States of America: Lippincott Williams & Wilkins, 2005: pp1014.
  3. American Society for Reproductive Medicine. Revised American Society for Reproductive Medicine classification of endometriosis: 1996. Fertil Steril 1997;67:817-821.
  4. Kennedy S. The patient’s essential guide to endometriosis. United Kingdom: Alden, 2003:pp42.
  5. Vercammen EE and D’Hooghe TM. Endometriosis and recurrent pregnancy loss. Semin Reprod Med 2000;18:363-368.
  6. Marcoux S, Maheux R and Berube S. Laparoscopic surgery in infertile women with minimal or mild endometriosis. Canadian Collaborative Group on Endometriosis. N Engl J Med 1997;337:217-222.
  7. Parazzini F. Ablation of lesions or no treatment in minimal-mild endometriosis in infertile women: a randomized trial. Gruppo Italiano per lo Studio dell’Endometriosi. Hum Reprod 1999;14:1332-1334.
  8. Hughes E, Fedorkow D, Collins J and Vandekerckhove P. Ovulation suppression for endometriosis (Cochrane Review). Cochrane Database of Systematic Reviews 2007; 3. Art. No.: CD000155. DOI: 10.1002/14651858.CD000155.pub2.
  9. ESHRE Guidelines, 2007 – online at
  10. Jacobson TZ, Barlow DH, Koninckx PR, Olive D and Farquhar C. Laparoscopic surgery for subfertility associated with endometriosis (Cochrane Review). Cochrane Database of Systematic Reviews 2002;4. Art. No.: CD001398. DOI: 10.1002/14651858.CD001398.
  11. Adamson GD, Hurd SJ, Pasta DJ and Rodriguez BD. Laparoscopic endometriosis treatment: is it better? Fertil Steril 1993;59:35-44.
  12. Guzick DS, Silliman NP, Adamson GD, Buttram-VC J, Canis M, Malinak LR and Schenken RS. Prediction of pregnancy in infertile women based on the American Society for Reproductive Medicine’s revised classification of endometriosis. Fertil Steril 1997;67:822-829.
  13. Osuga Y, Koga K, Tsutsumi O, Yano T, Maruyama M, Kugu K, Momoeda M and Taketani Y. Role of laparoscopy in the treatment of endometriosis-associated infertility. Gynecol Obstet Invest 2002;53 Suppl 1:33-39.
  14. Reid GD. Endometriosis and infertility. e-Report 2005;1:1-5.
  15. Beretta P, Franchi M, Ghezzi F, Busacca M, Zupi E and Bolis P. Randomized clinical trial of two laparoscopic treatments of endometriomas: cystectomy versus drainage and coagulation. Fertil Steril 1998;70:1176-1180.
  16. Chapron C, Vercellini P, Barakat H, Vieira M and Dubuisson JB. Management of ovarian endometriomas. Hum Reprod Update 2002;8:6-7.
  17. Hart R, Hickey M, Maouris P, Buckett W, and Garry R. Excisional surgery versus ablative surgery for ovarian endometriomata: a Cochrane Review. Hum Reprod, 2005;20:3000-3007.
  18. Vercellini P, Chapron C, De Giorgi O, Consonni D, Frontino G and Crosignani PG. Coagulation or excision of ovarian endometriomas? Am J Obstet Gynecol 2003b;188:606-610.
Thank you to the following for reviewing this article prior to its publication

Juan Garcia Velaso, IVI Madrid, Spain
Andrew Prentice, Consultant Gynaecologist, University of Cambridge, UK
Hugo C Verhoeven, Head of Reproductive Medicine, Med-Plus Krefeld, Germany

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