The precise cause of cervical dysplasia is not known, but it has been linked to exposure to certain strains of the human papillomavirus (HPV). HPV is a group of more than 100 viruses. They are called papillomaviruses because certain types may cause genital warts (papillomas), which are benign (noncancerous) tumors.

Certain types of HPV can trigger the cells on the cervix to behave abnormally. HPV is far more common than cervical dysplasia, with the majority of the sexually active population exposed to one or more types of HPV in their lifetime. However, not all HPVs will cause cervical dysplasia. It is likely that other elements cause or play a role in the development of cervical dysplasia. Though these elements have not yet been identified by the medical community, certain factors are known to increase the risk of cervical dysplasia. In addition to HPV exposure, they include:

• Multiple sexual partners.
  
  
• Early onset of sexual activity (younger than 18 years old).
  
  
• A history of other sexually transmitted diseases (STDs), such as genital herpes, chlamydia, gonorrhea, and human immunodeficiency virus (HIV).
  
  
• Immunosuppression (prevention of the activation of immune system responses). This is common in women with HIV or those taking drugs to prevent rejection of an organ transplant.
  
  
• Early childbearing (younger than 16 years old).
  
  
• Multiple pregnancies.
  
  
• Cigarette smoking.
  
  
• Low levels of folate (a B-complex vitamin essential for cell growth and reproduction) in red blood cells.
  
  
• Long-term use (five or more years) of birth control pills.

It is uncertain whether being born to a mother who took diethylstilbestrol (DES) is a risk factor. DES is a synthetic estrogen that was used from 1940 to 1970 to prevent some complications of pregnancy. Its use was discontinued after researchers discovered it to be ineffective and dangerous.

According to the Centers for Disease Control and Prevention, some studies have shown an increased risk of cervical dysplasia in women whose mothers took DES, though other studies have found no such link.