Understanding the causes of female and male infertility - Ruth Health

Understanding the causes of female and male infertility

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Fast facts:

  • Infertility is defined as the inability to get pregnant after a year or more of regular, unprotected sex. It affects both men and women.

  • Common causes of female infertility include disruption of ovarian function, uterine or cervical abnormalities, and fallopian tube obstruction.

  • Male infertility often stems from issues with sperm production.

  • Consult a reproductive specialist if you are 35 or older and have tried unsuccessfully to conceive for six months. Or, if you are younger than 35 and tried unsuccessfully to conceive for a year.

Infertility is defined as the inability to get pregnant after a year or more of regular, unprotected sex.

It can affect both men and women. Approximately:

  • One-third of infertility cases are attributed to a female reproductive factor.
  • One-third are attributed to a male reproductive factor.
  • One-third are attributed to a combination of both or to unknown causes.

A variety of factors may contribute to male and female infertility. Here’s a closer look at common fertility issues, including answers to frequently asked questions.

For an overview of infertility warning signs and treatment options, read What to Know About Infertility.

What are common female infertility issues?

Female infertility often stems from a complication with the ovaries, fallopian tubes, or uterus.

Disruption of ovarian function and issues with ovulation — the release of a mature egg from the ovaries — is a leading cause of female infertility.

  • This may occur as the result of hormonal disorders such as polycystic ovary syndrome (PCOS).
  • Other hormonal disorders that may disrupt ovarian function include hyperthyroidism, hypothyroidism, and hyperprolactinemia.
  • Excessive exercise, eating disorders, and stress may also impact ovulation.
  • Aging also affects ovarian function.

Uterine or cervical abnormalities can block the fallopian tubes or prevent a fertilized egg from implanting in the uterus.

  • This includes benign growths such as uterine fibroids and polyps. 
  • Endometriosis and adenomyosis can also affect the uterus and cervix, contributing to infertility. These are conditions in which tissue that normally lines the uterus grows elsewhere.

Fallopian tube obstruction is another key driver of female infertility. It may be caused by a history of pelvic infection, ruptured appendix, gonorrhea, chlamydia, or endometriosis.

Cancer of reproductive organs and their treatment may also affect a woman’s fertility.

There are also contributing factors unrelated to reproductive function, including the following:

  • Liver and kidney diseases
  • Blood diseases
  • Diabetes
  • Obesity
  • Nicotine and narcotic usage
  • Exposure to radiation

What are common male infertility issues?

Most cases of male infertility relate to issues with sperm production, including sperm quantity and quality. A low sperm count is typically defined as less than 15 million sperm per milliliter of semen.

There are multiple causes of abnormal sperm production or function.

This includes: 

  • Undescended testicles
  • Genetic defects
  • Sexually transmitted infections such as chlamydia, gonorrhea, or HIV, and other health conditions such as diabetes

Cancer treatment including radiation and chemotherapy can also affect sperm production.

Male infertility can also be an issue of sperm delivery. This is often due to sexual dysfunction including: 

  • Premature ejaculation
  • Genetic diseases such as cystic fibrosis
  • A blockage in the testicle
  • Damaged or injured reproductive organs

Do irregular menstrual periods affect female fertility?

The length of a menstrual period varies from one woman to another. It can also fluctuate from one month to another as a result of travel, stress, illness, or other factors. A cycle is considered irregular if it is shorter than 21 days or longer than 35.

Many women with irregular menstrual periods can become pregnant. However, an irregular period may be the result of a condition or health factor related to ovulation issues.

These can include PCOS, perimenopause, thyroid disease, high stress, or being severely overweight or underweight. There are fertility treatments designed to specifically target irregular ovulation.

An irregular period can also make it more difficult to track your cycle and pinpoint key fertile days. This can delay the timeline for conception.

How can a pelvic inflammatory disease affect pregnancy?

Pelvic inflammatory disease (PID) is an infection that occurs when bacteria spread from the vagina to the uterus, fallopian tubes, or ovaries.

It can develop any time bacteria enter the reproductive tract, including: 

  • A chlamydia or gonorrhea infection
  • IUD placement
  • Dilation and curettage procedure.

PID symptoms are often mild, and many women only discover that they have it after experiencing difficulty conceiving. Since PID can damage the female reproductive organs, it can lead to female infertility. 

Your risk for PID-related infertility increases with the number of times you develop the infection. Delaying treatment can also intensify the impact of PID on your fertility.

The most effective way to prevent PID is to get tested regularly for sexually transmitted infections. Also, use condoms if you are unsure about a partner’s sexual history and health.

How do fibroids cause infertility or miscarriage?

A uterine fibroid is a noncancerous growth of the uterus that most commonly develops during your reproductive years. While fibroids almost never develop into cancer, they can potentially increase your risk for infertility and/or pregnancy loss.

Fibroids are not a leading factor in female infertility. Many women who have had a uterine fibroid are able to conceive naturally — but 10% of all women affected by infertility have a fibroid. In some cases, they may be the only cause of female infertility.

The size and location of a fibroid can determine its impact on fertility. Fibroids inside the uterine cavity or within the wall of the uterus and more than 6 centimeters in diameter are likely to have the greatest effect.

A fibroid can contribute to female infertility in the following ways:

  • It can change the shape of the cervix, which can affect how many sperm are able to enter the uterus.
  • It can change the shape of the uterus, which can, in turn, affect the movement of sperm and/or an embryo.
  • It can affect blood flow to the uterine cavity, which may decrease an embryo’s ability to implant in the uterine wall or to grow.
  • It can block the fallopian tubes.
  • It can change the size of the uterine cavity’s lining.

About 2-12% of pregnant women have a fibroid. Having a fibroid during pregnancy will not necessarily lead to complications or pregnancy loss. 

It depends significantly on whether a fibroid becomes larger. This makes it more likely to affect a baby’s position in the uterus. Fibroids that grow usually do so within the first 12 weeks of pregnancy.

How does a woman's fertility vary with age and is it possible to become pregnant after 35?

The quality and quantity of a woman’s eggs steadily decline beginning around the age of 32. These changes increase more rapidly from about 37 onwards. 

Infertility affects about: 

  • 22% of couples in which the female partner is between the ages of 30-39
  • 13% of couples in which the female partner is younger than 30. 

Age also plays a role in the success rates of in vitro fertilization (IVF).

Despite the correlation between infertility and age, women can become pregnant after 35, or even 40. In fact, it’s become increasingly common to start your family-building journey at a later age. Many women try to conceive after 35.

It is recommended to seek fertility treatment after six months of trying unsuccessfully to conceive naturally if you are 35 or older. For those under 35, it’s recommended to seek treatment after a year of trying to conceive.

If you are over 40, you may consider scheduling an evaluation of your fertility before trying to conceive.

Age can also factor into male infertility. Couples in which the male partner is 40 or older are more likely to experience difficulty getting pregnant.

Ruth Health is here to provide you with expert, evidence-based maternal care and advice. Interested in learning more about a particular topic? Send us an email at hello@ruthhealth.com.

If you have additional questions regarding infertility, consult your physician or trusted healthcare professional to discuss diagnosis and treatment options.

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