Common Causes of Infertility

Each month, even fertile couples can expect only a 20 to 25 percent chance of becoming pregnant. All reproductive organs and processes must bring their “A” game for fertilization and pregnancy to occur. The ovaries must release a healthy egg, which then must come in contact with sperm in the right place at the right time (in a fallopian tube) and then travel to a supportive uterine environment.

Millions to hundreds of millions of sperm that enter the vagina must find their way to the cervical canal. The ones that survive must then gain speed and travel through the uterus to the fallopian tubes, fighting other sperm to be the first to penetrate the egg and cause fertilization.

When one or more parts of this well-orchestrated process falls short on a regular basis, infertility is the result. The causes are well distributed. About 30 percent of the time, infertility is caused by a female factor, 30 to 40 percent of diagnoses are linked to a male factor, and remaining infertility cases are a combination of factors from both partners. The Bethesda Fertility Center performs full evaluations of both partners for this reason.

Female Infertility

The below causes are some of the more common barriers to female fertility. Treatment options range from reproductive surgeries, to intrauterine inseminations to high-tech procedures involving in vitro fertilization. Visit our treatment and procedures page for more information.

  • Uterine causes. Abnormal anatomy of the uterus; presence of polyps and fibroids.
  • Endometriosis. A condition where the uterine tissue implants and grows outside the uterus, potentially affecting the function of the sperm, egg and ovaries, uterus and fallopian tubes.
  • Polycystic ovary syndrome (PCOS). A hormonal condition in which the body produces too much androgen, which can affect ovulation. PCOS is also associated with insulin resistance and obesity.
  • Fallopian tube damage. Damage to the fallopian tubes, such as scarring from pelvic infections, endometriosis or pelvic surgeries, can prevent the union of egg and sperm.
  • Ovulation disorders. The inability of the ovaries to release eggs (anovulation) can be caused by injury, tumors, hormonal disorders, excessive exercise and starvation.
  • Hormonal causes. The hormones required for ovulation and thickening of the uterine lining may not be present in the right amounts, affecting both ovulation and successful implantation of a fertilized egg (pregnancy).
  • Early menopause. Although the cause is often unknown, certain conditions are associated with early menopause, including immune system diseases, radiation/ chemotherapy treatment and smoking.
  • Pelvic adhesions. Pelvic infection, appendicitis or abdominal/pelvic surgery can cause scar tissue, which may impair fertility.

Female infertility also can be caused by other factors, including the following: sexually transmitted infections, medications (although temporary), thyroid disorders, cancer and cancer treatment, anatomical issues (i.e., cervical abnormalities) and medical conditions such as sickle cell disease, kidney disease and diabetes.

Male Infertility

About 90 percent of male infertility cases are due to low sperm counts, poor sperm quality (movement/shape) or both. A semen analysis should be done very early in the evaluation of a couple seeking infertility treatment, preferably as one of the very first tests and clearly before any invasive or uncomfortable tests are performed on the woman (HSG or surgery). Visit our male infertility treatments page to learn about sperm abnormalities and how they are diagnosed.

The good news is that more than 70 percent of male infertility cases are treatable thanks to scientific advancements such as intracytoplasmic sperm injection and hamster zona sperm cryopreservation, which address sperm quality and sperm count issues.

The remaining 10 percent of male infertility cases can be caused by a number of factors, including anatomical issues (i.e., undescended testicles, congenital absence of vas deferens), hormonal imbalances, genetic defects and lifestyle/environmental factors. The below are just a few examples.

General health and lifestyle issues. Examples include poor nutrition, obesity, and use of alcohol, tobacco and drugs. Conversely, generally healthy practices, such as long distance running, can contribute to lower sperm counts and testosterone levels.

Overexposure to environmental factors. Besides pesticides and other chemicals, seemingly harmless activities such as frequent exposure to heat via saunas or hot tubs can elevate core body temperature and impair sperm production and count.

Cancer-related damage. Both radiation and chemotherapy treatment for cancer can impair sperm production. The closer radiation treatment is to the testicles, the higher the risk of infertility. Removal of one or both testicles due to cancer also may affect male fertility.

Sexually transmitted diseases. Chlamydia, gonorrhea and other STDs can block sperm-carrying ducts with inflammation and scar tissue. Men with symptoms such as burning on urination or discharge from the penis should see a doctor as soon as possible to minimize long-term damage.

Unknown Causes of Infertility

In about 20 percent of infertility cases, a cause cannot be determined. However, this does not mean that all hope is lost. A wide range of treatment options is available, and a recommended treatment plan will consider:

  • Fertility evaluation and testing of both partners
  • Individual patient characteristics such as age and side-effect profiles (i.e., multiple pregnancy)
  • Potential lifestyle changes
  • The couple’s preference for the degree of treatment invasiveness
  • Financial considerations

Before a diagnosis of unexplained fertility is made, couples should undergo a semen analysis, ovulation testing, assessment of ovarian reserve, and imaging tests to assess for tubal and uterine factors (i.e., tubal damage, endometriosis). If these tests return normal results, yet the couple still experiences infertility, one explanation could be that there is no one single, obvious cause, but rather, multiple minor issues that do not show up on standard diagnostic testing. The couple’s infertility may be a result of undetectable aberrations in their respective reproductive systems that when combined, reduce the couple’s fertility potential.