Risk Factors and Protective Factors

Reviewed by: HU Medical Review Board | Last reviewed: June 2018

Although the underlying cause of endometriosis is not well understood, there are several risk factors and protective factors that may affect an individual's chances of developing endometriosis. Risk factors are characteristics or behaviors that an individual may have that increase the risk of developing a condition. Risk factors can be modifiable and non-modifiable. Modifiable risk factors are things that can be changed, such as changes in diet or exercise routines. Non-modifiable risk factors cannot be changed, and include things like race, age, ethnicity, and genetics.

Protective factors are things that decrease an individual's risk of developing a condition, or that decrease the negative impact of a risk factor. Protective factors may include things like maintaining a healthy body weight or seeking medical attention for other underlying conditions. There are several theorized risk and protective factors in relation to endometriosis.

Risk factors

Possessing certain risk factors may increase a woman's risk of developing or being diagnosed with endometriosis. Some of these risk factors include:

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  • Low body mass index (very low body weight)
  • Having your first period at an early age (also called early menarche and is considered to be having a first period at 11 years old or younger)
  • Having a low birth weight
  • Experiencing later than average menopause (average menopause is around 51 years old)
  • Having shorter menstrual cycles that last less than 28 days
  • Having a family history of endometriosis (having a mother, sister, grandmother, aunt, etc. who has endometriosis)
  • Having prolonged periods (periods that last longer than a week)
  • Experiencing periods with very heavy menstrual flow
  • Being exposed to synthetic estrogens in utero
  • Being exposed to environmental pollutants like dioxins or pesticides
  • Hormonal imbalances, such as high estrogen and low progesterone levels
  • Never having a child (or not having a child yet)
  • Having a condition that affects normal menstrual blood flow out of the body
  • Having an immune system that doesn't function properly
  • Experiencing constant inflammation
  • Experiencing abnormal development of the female reproductive system (also called müllerian anomalies)1-4

The incidence and prevalence of endometriosis does not appear to be associated with race or ethnicity. This means, endometriosis does not appear to affect one race or ethnicity of women more than any other. Slight variations in the incidence of endometriosis in different racial or ethnic groups are often thought to be related to genetic or environmental-related risk factors, however, overall, a racial or ethnic bias has not been found for endometriosis.5

Protective factors

Protective factors for endometriosis include things that reduce inflammation, and decrease rates of ovulation or levels of estrogen in the body. Some of these protective factors include, but are not limited to:

  • Giving birth or multiple births
  • Using oral contraceptives
  • Having a tubal ligation
  • Having a hysterectomy
  • Using nonsteroidal anti-inflammatory medications (NSAIDs)
  • Practicing prolonged breast feeding
  • Exercising regularly
  • Having a history of amenorrhea (an absence of regular periods that is often encountered by athletes)
  • Having a low percentage of body fat
  • Avoiding excessive amounts of alcohol or caffeine2,4

It's important to note that possessing or working toward some of these protective factors does not guarantee prevention of endometriosis. Individuals with many, or all, of these protective factors may still develop the condition. Additionally, not all risk or protective factors are considered equal. For example, some risk factors may be associated with the higher risk of developing the condition than others, just like some protective factors may be associated with a greater decrease in risk of developing endometriosis. For a more complete understanding of your potential risk factor and protective factor profiles, consult your doctor or healthcare team.