Endometriosis is a common female problem which is thought to have increased somewhat in modern times.  It is a more common problem for better educated women for some of the reasons described below.  It is caused by bits of uterine tissue being refluxed into the abdominal cavity and implanting.  The tissue then bleeds each month causing pain and adhesions.  While endometriosis occurs in 10%-15% of American women, serious cases are fewer.  Endometriosis which starts at a younger age ends up causing more problems, including infertility.  I will not cover treatment, which, while far from ideal, does help.

Many factors help cause endometriosis.  It is more common in taller and thinner childless women, in women who started menstruating at an earlier age, and in women who have short cycles but with longer periods of menstruating and painful menstruations.  Genetics plays an important role with daughters of mothers with endometriosis being five times more likely than average to develop the disease.  Early childbirth has been recommended for such daughters both to decrease their risk of endometriosis and to avoid total infertility.

A few factors have been found to decrease the risk of endometriosis.  Women who exercise vigorously for several hours per week are much less likely to become victims.  Having children, and breastfeeding each considerably decreases the risk, probably due to increasing the ease with which monthly menstruation can be discharged from the uterus for several years after each pregnancy.  Eating yogurt, green vegetables, and fruit daily helps prevent endometriosis.  Avoid mammal meat: beef and pork double the risk of endometriosis.  Combining these above healthy habits should reduce the risk of endometriosis by more than 90%.

Avoiding sexual intercourse during menstruation reduces the risk probably by reducing reflux of uterine tissue into the abdomen, although masturbation might be OK.  The birth control pill and IUDs seem to somewhat increase the risk, although birth control pills can temporarily suppress the symptoms.  Diaphragms are probably better, especially when combined with avoiding sex during menstruation.  Tampons seem to increase endometriosis; so pads are probably preferable, especially for women still wanting to have children.  

Starting having periods at an early age, having a short menstrual cycle, and exposure to PCB chemicals all increase the risk, but an individual can't easily affect the occurence of any of these.

Birth Control Pill and IUD Users Small Increased Risk: In a case-control study of 376 women with laparoscopically confirmed endometriosis vs. 522 women the relative risk (RR) of endometriosis for contraceptive users was 1.6; for ex-contraceptive users (RR 1.7) and for current users being 0.9. In comparison with never IUD users, the risk for ever users was 1.3, and no clear relation emerged with duration of use. Likewise, no association was observed between barrier method of contraception and risk of endometriosis although the trend was favorable for diaphrams being protective (RR ever vs. never users 0.5). The role of selection and other biases should be considered in the interpretation of epidemiological data on the role of contraceptives on the risk of endometriosis. Contraceptive methods and risk of pelvic endometriosis. Parazzini F, Ferraroni M, Bocciolone L, Tozzi L, Rubessa S, La Vecchia C. Milano, Italy. Contraception. 1994 Jan;49(1):47-55

Birth Control: IUDs a Risk Factor: 3384 multiparous women underwent laparoscopy for tubal sterilization. Endometriosis was detected in 126 patients (3.7%). 504 patients with no evidence of endometriosis were randomly selected from a group of women who underwent sterilization. Most endometriosis lesions were minimal. Factors associated with an increased risk for endometriosis included: advanced age (odds ratio [OR] 2.0), Asian race (OR 8.6), long cycle length (OR 1.8), one live birth (OR 2.2), long duration of intrauterine device use (OR 3.0), and long duration of uninterrupted menstrual cycles (OR 2.9). Present oral contraceptive use was protective for disease (OR 0.5). The role of these factors varied among different disease locations (ovary, uterus and tubes, posterior broad ligaments and cul-de-sac), and depth (superficial or deep). Epidemiology of endometriosis among parous women. Sangi-Haghpeykar H, Poindexter AN 3rd. Baylor. Obstet Gynecol. 1995 Jun;85(6):983-92

Birth Control Pills May Increase Risk; Having Children or Even Miscarriages Lowered Risk: Women with primary or secondary infertility (n = 393) or chronic pelvic pain (n = 424), requiring laparoscopy, consecutively observed found 345 had endometriosis. For birth control pills, 47.5% women with endometriosis vs. 29.4% without the disease reported ever using oral contraception. In comparison with never users the estimated odds ratios (OR) of endometriosis were 1.8 in current users and 1.6 in ex-users. No clear relation emerged between duration of oral contraceptive use and risk of endometriosis. Italian Endometriosis Study Group. Parazzini F, Di Cintio E, Chatenoud L, Moroni S, Mezzanotte C, Crosignani PG. Universita di Milano, Italy. Br J Obstet Gynaecol. 1999 Jul;106(7):695-9. Multiparous women in the same study had endometriosis less frequently than nulliparous, the estimated odds ratios (OR) were respectively 0.9 and 0.4 in women reporting one and two or more births. In comparison with women reporting no spontaneous abortion, the estimated OR was 0.3 in those who reported > or =1 miscarriage. In comparison with women reporting menstrual cycles lasting > or =25 days subjects with totally irregular menstrual cycles had a reduced risk of endometriosis (OR 0.6). No significant association emerged between smoking, age at menarche and risk of endometriosis. Eur J Obstet Gynecol Reprod Biol. 1999 Apr;83(2):195-9

Breastfeeding Duration Strongly Reduces Endometriosis Risk as does Having More Children: Analyzing 10 years of prospective data from the Nurses' Health Study II every 2 years from 116,678 women ages 25-42, 1,721 cases of laparoscopically confirmed endometriosis were reported. Greater incidence was observed among women with an earlier age at menarche (RR 1.3 comparing menarche at age < 10 to age 12 years; p < .001) and shorter cycle length during late adolescence (RR 1.3 comparing < 26 days to 26-31 days). Time to cycle regularity was not associated with risk. Among parous women, a linear decrease in risk was observed with number of liveborn children (RR 0.5 comparing > 3 with 2 children; p < .001) and lifetime duration of lactation if time since last birth was less than 5 years (RR 0.2 comparing > 23 months with never; p < .001). Reproductive history and endometriosis among premenopausal women. Missmer SA, Hankinson SE, et al. Brigham and Women's Harvard. Obstet Gynecol. 2004 Nov;104(5 Pt 1):965-74.

Childless with Short Cycles and Long, Heavy Periods Most at Risk: Temporal trends suggest an increase among women of reproductive age. This could be explained-at least in part-by changing reproductive habits. Numerous epidemiological studies have indicated that nulliparous women and women reporting short and heavy menstrual cycles are at increased risk of developing endometriosis. These epidemiological findings strongly support the menstrual reflux hypothesis. Additional evidence in favor of this theory includes the demonstration of viable endometrial cells in the menstrual effluent and peritoneal fluid, experimental implantation and growth of endometrium within the peritoneal cavity, observation of some degree of retrograde menstruation in most women undergoing laparoscopy during menses, and an association between obstructed menstrual outflow and endometriosis. Endometriosis: epidemiology and aetiological factors. Vigano P, Parazzini F, Somigliana E, Vercellini P. University of Milan, Italy. Best Pract Res Clin Obstet Gynaecol. 2004 Apr;18(2):177-200

Daughters Five Times More Likely to Have Endometriosis if Mother Did: 528 women with endometriosis and 149 controls gave information about family members. Endometriosis or adenomyosis was disclosed in 3.9% of mothers of cases and in 0.7% of mothers of controls, in 4.8% of sisters of cases and in 0.6% of sisters of controls. The odds ratio of endometriosis in a first-degree relative was 7.2. Severe manifestations of endometriosis were found more often among patients with a positive family history than among those without (26% versus 12%, p < 0.01). The familial risk of endometriosis. Moen MH, Magnus P. University of Oslo, Norway. Acta Obstet Gynecol Scand. 1993 Oct;72(7):560-4

Diet: Green Vegetables and Fruit Good; Mammal Meat Bad: In two case-control studies from Northern Italy of 504 women under age 65 with a laparoscopically confirmed endometriosis, compared to women in the lowest tertile of intake, a higher intake of green vegetables [odds ratio (OR) = 0.3 for the highest tertile of intake] and fresh fruit (OR = 0.6) reduced the risk, whereas an increase in risk was associated with high intake of beef and other red meat (OR = 2.0) and ham (OR = 1.8). Consumption of milk, liver, carrots, cheese, fish and whole-grain foods, as well as coffee and alcohol consumption, were not significantly related to endometriosis. Selected food intake and risk of endometriosis. Parazzini F, Chiaffarino F, et al. Universita di Milano, Italy. Hum Reprod. 2004 Aug;19(8):1755-9. Ed: Fortunately, this is exactly the diet that is good in general.  Humans should not eat mammal meat since mammals are close relatives and eating close relatives is bad for your health.

Earlier Endometriosis Onset, Worse Disease; Diagnosis Delayed: Data from over 7,000 confirmed cases clearly show that delay in diagnosis (the average time to diagnosis is >9 years) is a major problem and that current treatments are far from satisfactory.  Impact of endometriosis on women's health: comparative historical data show that the earlier the onset, the more severe the disease. Ballweg ML. Best Pract Res Clin Obstet Gynaecol. 2004 Apr;18(2):201-18

Early Menarche, Frequent Periods, No Children Risk Factors: In a survey of 4034 Norwegian women born in 1950, endometriosis was reported by 2.0% of the women. There was a significant association between endometriosis and menarche before age 13, and frequent menstrual periods. Nulliparity was more common in women with endometriosis as were infertility problems and pelvic pain. No significant association was found between endometriosis and exercise, smoking, body mass index and education. There was a high risk for women with endometriosis having had cervical conization or gynecological laparotomies such as infertility surgery, operations on ovaries as well as hysterectomies. Epidemiology of endometriosis in a Norwegian county. Moen MH, Schei B. University Hospital of Trondheim, Norway. Acta Obstet Gynecol Scand. 1997 Jul;76(6):559-62

Exercise: High-Intensity Physical Exercise Markedly Reduces Endometriosis Risk: In a case-control study (77 cases, 735 controls) of females aged 18-39 years, high-intensity physical activity during the 2 years prior to the reference date had a 76% reduced endometrioma risk (odds ratio = 0.24) compared with women who engaged in no high-intensity activity. A nonsignificant 53% reduction in risk was observed for women who reported such activity at ages 12-21 years (odds ratio = 0.47). Activities of lower intensity, frequency, and duration were not associated with a woman's risk of endometrioma. Recreational physical activity and endometrioma risk. Dhillon PK, Holt VL. Seattle, WA, USA. Am J Epidemiol. 2003 Jul 15;158(2):156-64

Exercise Four Hours Per Week Helps: In a case-control study, cases were 50 women with infertility-associated endometriosis. The primary control group consisted of 89 fertile women without endometriosis, and an alternate control group consisted of 47 infertile women without endometriosis. The risk of endometriosis was positively associated with height (OR), 2.8 per 10 cm increase and inversely associated with weight (OR, 0.7 per 10 kg increase) and body mass index (OR, 0.7 per 5 kg/m2 increase). There was an inverse association with exercise (OR, 0.6), but the effect was limited to women who exercised > or = 4 hours per week (OR, 0.4). Endometriosis was not associated with either smoking or alcohol consumption. Epidemiologic determinants of endometriosis: a hospital-based case-control study. Signorello LB, Harlow BL, Cramer DW, Spiegelman D, Hill JA. Harvard. Ann Epidemiol. 1997 May;7(4):267-741

Exercise: Vigorous Exercise During Menses a Risk Factor: A case-control study involving 203 cases of pelvic endometriosis  and 406 randomly selected and age-matched c controls found that women characterized by earlier menarche (< or = 12 years) and longer period (> or = 8 days) were found to be associated with an elevated incurring risk, and a trend of increasing risk associated with primary dysmenorrhea (RR = 2.1 for mild to moderate and RR = 5.2 for severe dysmenorrhea), energetic physical activity during menstruation (RR = 2.1), and allergic diathesis (RR = 1.8) was seen. An inverse relationship was observed between the number of pregnancies and risk of endometriosis, and the protective effect was most significant when only the number of full-term pregnancies was counted. A case-control epidemiologic study of endometriosis. Han M, Pan L, Wu B, Bian X. Beijing. Chin Med Sci J. 1994 Jun;9(2):114-8

Genetics Plays a Role for Some Women: Endometriosis is a complex gynecologic disorder that affects as many as 10-15% of premenopausal women. Epidemiologic studies have confirmed that this disease is a genetic disorder of polygenic/multifactorial inheritance. Genetics of endometriosis: heritability and candidate genes. Bischoff F, Simpson JL. Baylor College of Medicine. Best Pract Res Clin Obstet Gynaecol. 2004 Apr;18(2):219-32

Genetics: Hereditary Tendency Found, Early Childbirth Important: An Iceland genetic study of 750 women with endometriosis found a greater than 400% increase in a sister who has a sister with the disease and a 50% increase if a cousin has the disease. Disease is passed by both men and women to their offspring. Researcher advises early childbirth for women with relatives who have disease since disease progresses and fertility decreases as victims age. It is common for 10 years to elapse between first symptom and diagnosis. Human Reproduction 2/02

Heavy Periods, Ectopic Pregnancy, Pungent Food, Not Dressing Warmly During Menses Risk Factors: A hospital-based pair matched case-control study of 100 pairs of female patients with endometriosis and controls found higher rates of endometriosis for high educational level, history of ectopic pregnancy, short menstrual cycle, menorrhagia, dysmenorrhea, not warmly dressed during menses, depression, history of coitus during menstruation or puerperium and heavy pungent food. The multivariate analysis confirmed that the risk factors associated with endometriosis were menorrhagia, not warmly dressed during menses, depression during menstruation, heavy pungent food, and history of ectopic pregnancy (OR = 0.388, 3.066, 4.292, 2.742, 3.612, respectively). A case-control study on risk factors of endometriosis in Chengdu. Wang H, Wu Y, Chen X, Guo Y, Song X, Tian C, Wang J. Sichuan Da Xue Xue Bao Yi Xue Ban. 2003 Oct;34(4):727-9. Ed: Perhaps being out in the cold inadequately dressed during the menses increased reflux into the abdomen.

Immune System Involved: Endometriosis is a benign gynecologic disorder with ectopic growth of misplaced endometrial cells. The immune system is involved in endometriosis. Although numerous studies have shown alterations in cell-mediated and humoral immunity in subjects with endometriosis, the importance of these changes remains obscure.  Immunology of endometriosis. Paul Dmowski W, Braun DP. Rush Medical College. Best Pract Res Clin Obstet Gynaecol. 2004 Apr;18(2):245-63

Lead Exposure Not a Risk Factor: In a study of rhesus monkeys, endometriosis was not significantly associated with low level lead exposure (P=.36). Neurotoxicol Teratol. 2003 Sep-Oct;25(5):561-70

Monkeys: Endometriosis High in Monkey Colony: A total of 314 records collected over a 15-year period were analyzed, yielding 66 monkeys with histologically verified endometriosis and 248 control subjects. Endometriosis increases progressively across the life span, ultimately impacting 21-45% of aged monkeys over 20 years of age. Profile of endometriosis in the aging female rhesus monkey. Coe CL, Lemieux AM, Rier SE, Uno H, Zimbric ML. University of Wisconsin. J Gerontol A Biol Sci Med Sci. 1998 Jan;53(1):M3-7. Ed: Baboons get endometriosis, too.

Monkeys: Endometriosis Helped by Lactobacillus: Monkeys with endometriosis had a significantly lower Lactobacilli concentrations and higher Gram-negative bacteria concentrations. There was a higher prevalence of intestinal inflammation in monkeys with endometriosis in comparison to healthy controls. Endometriosis is associated with an altered profile of intestinal microflora in female rhesus monkeys. Bailey MT, Coe CL. University of Wisconsin. Hum Reprod. 2002 Jul;17(7):1704-8. Ed: While lactobacillus may not protect against the development of endometriosis, the amazing thing is that not a single study listed on PubMed has ever explored this possibility!

PCBs Might be a Cause: In a study of 84 eligible women ages 18-40 undergoing laparoscopy, 32 had visually confirmed endometriosis. Women in the third tertile of anti-estrogenic PCBs had a markedly elevated risk [OR 3.77]. Risk remained elevated after controlling for gravidity, current cigarette smoking and serum lipids (OR 3.30). Environmental PCB exposure and risk of endometriosis. Louis GM, Weiner JM, et al. National Institute of Child Health & Human Development, Rockville, MD. Hum Reprod. 2005 Jan;20(1):279-85. Similar findings in Biomarkers. 2003 Nov-Dec;8(6):529-34.

Peristaltic Activity in Excess May Cause Some Endometriosis: Peristaltic activity of the nonpregnant uterus serves to directed transport of spermatozoa into the tube ipsilateral to the dominant follicle and high fundal implantation of the embryo, but may cause retrograde menstruation. Leyendecker G, Kunz G, et al Universities of Frankfurt and Heidelberg/Mannheim. Ann N Y Acad Sci. 2004 Dec;1034:338-55

Pregnancy Protective: In 313 women with endometriosis, rates rose between age 25-29 and age 40-44 (0.13 vs. 0.81; p .001), so that the relative risk (RR) at 40-44 years was 6.1. Diaphragm use and endometriosis were not associated. Endometriosis was less likely to occur during pregnancy (RR = 0.05) and 4 years after pregnancy (RR = 0.4-0.6) than at most other times. Current or recent (=or 12 months) use of oral contraceptives (OCs) appeared to protect against endometriosis (RR = 0.4). Yet, the risk of developing endometriosis was greater at least 1 year after stopping OC use (RR = 1.4-1.8). The researchers believed, however, that OCs only temporarily concealed the symptoms of endometriosis. Like OC use, current and recent IUD users and women who had last used an IUD 25-48 months earlier had a low risk of developing endometriosis (RR = 0.4 an 0.5, respectively). The RR increased for those who had last used an IUD at least 49 months prior to developing endometriosis (1.4). The researchers surmised that, since pain and bleeding are common clinical features of IUD use a endometriosis, providers removed the IUD rather than perform a laparoscopy or laparotomy to detect endometriosis, thereby accounting for the apparent protective effect. Further, providers probably diagnosed endometriosis later in IUD users because of the shared clinical features. Epidemiology of endometriosis in women attending family planning clinics. Vessey MP, Villard-Mackintosh L, Painter R. Oxford. BMJ. 1993 Jan 16;306(6871):182-4

Sex During Menses Increases Endometriosis and Infertility: 498 female patients were interviewed. Endometriosis and tubal infertility factor were diagnosed on laparoscopy or laparotomy. The frequency of endometriosis was higher (P less than .05) in patients with coitus during menses (17.5%) than in women never having sex during menses (10.9%). The frequency of PID was not different. The frequency of tubal infertility factors was higher in the PID group (78.4%) than in the non-PID group (30.4%) (P less than .001). Endometriosis was associated with an increase in tubal infertility factors (47.9% vs. 33.3% in the nonendometriosis group) but to a lesser degree than PID. Coitus during menses. Its effect on endometriosis and pelvic inflammatory disease. Filer RB, Wu CH. Thomas Jefferson University. J Reprod Med. 1989 Nov;34(11):887-90

Sex During Menses, Tampons Decrease Endometriosis: In a case-control study of 2,012 members of the Endometriosis Association and friends, there was no difference between study groups concerning douching practices. However, cases were less likely than controls to report sometimes or often engaging in sexual behaviors during menstruation (p = 0.002, OR = 1.5), and sexual behaviors during menstruation that included orgasm (p = 0.001, OR = 1.5). Cases were also less likely than controls to report using only tampons (p < 0.0001, OR = 2.6). Sexual activity, orgasm and tampon use are associated with a decreased risk for endometriosis. Meaddough EL, Olive DL, et al. Southern Connecticut State University. Gynecol Obstet Invest. 2002;53(3):163-9.  Ed: I am uncomfortable with this retrospective research design since many of the endometriosis victims may have alterred their practices due to the disease and then not remember accurately their practices before disease development.

Tall, Thin, Childless Women with Painful Periods: Women with endometriosis may be taller and thinner. Menstrual factors reported to increase risk include dysmenorrhea, early menarche, and shorter cycle lengths. Dysmenorrhea could be either a disease symptom or a manifestation of outflow obstruction. Nulliparity could be either a consequence of disease or a cause since nulliparous women would not have the benefit of cervical dilation associated with labor and delivery. The epidemiology of endometriosis. Cramer DW, Missmer SA. Harvard Medical School. Ann N Y Acad Sci. 2002 Mar;955:11-22; discussion 34-6, 396-406

Tampons Thought to be a Risk Factor by One Study: Recent research (van Rijswijck & Botha, 1997) indicated that a correlation between the use of tampons during menstruation and endometriosis exists. Endometriosis in tampon users. Roets L, van Rijswijck O. South Africa. Curationis. 1999 Mar;22(1):12-5

Tampon Use, Heavy Flow, Cramps Linked to Endometriosis: In a study of 101 women with endometriosis, among women under age 30, using friend controls, there was an elevated risks for menstrual flow > or = 6 days per month (OR = 2.5), heavy flow (OR = 2.5), severe cramps (OR = 2.5), increasing symptoms (OR = 6.6), and tampon use for more than 14 years (OR = 3.6). Risks were also elevated for women age 30 and over, but not to the same degree as among younger women. Menstrual cycle characteristics and the risk of endometriosis. Darrow SL, Vena JE, Batt RE, Zielezny MA, Michalek AM, Selman S. SUNY, Buffalo. Epidemiology. 1993 Mar;4(2):135-42

Treatment

Antileukotriene Therapy Helped Rats: In rats given experimental endometriosis, those treated with a leukotriene receptor antagonist had a significant decrease in stromal proliferation when compared with nontreated rats. The treated rats showed not only the suppression of infiltration and activation of mast cells but also widespread apoptosis of proliferative fibroblasts in the lesions. Light and electron microscopic evaluation of antileukotriene therapy for experimental rat endometriosis. Ihara T, Uchiide I, Sugamata M. Japan. Fertil Steril. 2004 Mar;81 Suppl 1:819-23