Causes of Infertility

Infertility can be due to reproductive health problems in the male (1/3 of cases) or female (1/3 of cases), a combination of both, or other unexplained factors (the latter 2 making up the final 1/3 of cases). If you're having trouble getting pregnant, it's important to talk with your doctor about potential causes and possible treatment options.

Common causes of female infertility

In about 1/3 of cases, female reproductive health issues are the cause of infertility. Some common causes of female infertility include:

  • Endometriosis

    A condition in which cells from the lining of the uterus attach and grow in other areas of the body. This tissue growth can lead to damage in the reproductive organs, which can interfere with or prevent pregnancy. Signs can include painful and/or abnormal periods and abdominal cramping, although some women experience no symptoms.

  • Polycystic ovary syndrome, or PCOS

    A condition in which the body's sex hormones are not balanced. Signs of PCOS may include absent or irregular periods, acne, and changes in body and facial hair. With PCOS, normal ovulation is disrupted when eggs in the follicles do not mature and release, instead forming small cysts in the ovaries.

  • Primary ovarian insufficiency (POI) or premature ovarian failure (POF)

    A loss of normal ovarian function (decreased estrogen, irregular egg production) prior to age 40. Signs of POI such as irregular periods, hot flashes, and difficulty concentrating are similar to those seen with menopause.

  • Fallopian tube damage or blockage

    Internal blockage or inflammation of the fallopian tube, most often caused by pelvic inflammatory disease (PID).

  • Uterine fibroids

    Noncancerous tissue growths in the uterus that can interfere with attachment of a fertilized egg to the uterus (implantation) or interfere with the sperm's ability to travel to the fallopian tubes. Signs include heavy and/or longer-lasting periods, pelvic pain, painful intercourse, and frequent urination, although some women have no symptoms.

  • Pelvic adhesions

    Bands of scar tissue that can bind the abdominal organs, usually after surgery or pelvic infection, and may cause long-term pelvic pain.

  • Elevated prolactin, or hyperprolactinemia

    High levels of prolactin (the hormone that causes breast milk production) in women who aren't pregnant or lactating can cause impaired ovulation.

  • Reproductive tract abnormalities

    Reproductive tract abnormalities occur when the reproductive system does not form as it should. Common forms include müllerian agenesis (the uterus and fallopian tubes do not form) and müllerian duct fusion disorders (the müllerian ducts do not come together correctly). Fusion disorders include didelphic uterus (a complete duplication of the uterus, cervix, and sometimes the vagina), bicornuate uterus (two uteri share a single cervix and vagina), septate uterus (a fibrous band of tissue divides the uterus), and arcuate uterus (a dent on the top of the uterus).

Common causes of male infertility

Male infertility is responsible for about 1/3 of infertility cases. Common causes may include:

  • Low sperm count

    Defined as fewer than 20 million sperm per milliliter of semen, low sperm count means reduced odds that one will fertilize an egg.

  • Abnormal sperm movement or shape

    Atypical sperm shape or damaged sperm motility (movement) can affect the sperm's ability to travel to and/or penetrate the egg.


These causes can be the result of certain medical conditions, including:

  • Varicocele

    A swelling of the testicular veins that can lead to improper cooling of the testicles and decreased sperm count and function.

  • Infection

    Certain types of infection can interfere with sperm production or create scarring that blocks sperm passage.

  • Retrograde ejaculation

    When semen enters the bladder instead of emerging through the penis.

  • Hormone imbalance

    Disorders of the male sex hormones, including low levels of testosterone.

If you or your partner are experiencing any signs or symptoms of the above conditions, it's important to talk with your doctor right away.

Health and lifestyle factors

Besides certain medical conditions, many other health issues can affect male and female fertility, including:

  • Age
  • Smoking
  • Alcohol consumption
  • Stress
  • Being overweight or underweight
  • Certain medications