Prostock-studio / ShutterstockIn 35% of infertility cases, it’s related to a combination of factors in both the man and woman.
- An estimated 15% of couples experience infertility at some point and sometimes, there is no explanation for infertility.
- Frequent bicycle riding, poor diet, testosterone and prostate cancer medications, as well as certain medical conditions can affect fertility in men.
- Medical conditions such as PCOS, diabetes, cystic fibrosis, or autoimmune disorders are all associated with infertility in women.
- Couples unable to conceive on their own after a year of trying should seek help from a fertility specialist.
- This article was reviewed by Felice Gersh, MD, an OB-GYN and founder and director of the Integrative Medical Group of Irvine.
- Visit Insider’s homepage for more stories .
Infertility is a condition that affects an estimated 15% of couples worldwide. Here’s what you need to know about how common infertility is, who it affects, and what factors can play a role.
Factors that can cause infertility and men and women
According to the Centres for Disease Control and Prevention (CDC), in 35% of infertility cases, it’s related to a combination of factors in both the man and woman.
And in some cases, the exact cause is not known. “Sometimes, there is no explanation,” says Maryanne George, a certified nurse-midwife with Spectrum Health.
What is known, however, is that there are certain medical conditions that can contribute to infertility in both men and women, such as:
- Hormonal disorders and pituitary, adrenal, and hypothalamus dysfunction.
- Medical conditions such as diabetes, cystic fibrosis, and autoimmune disorders.
- Pelvic infection
- Cancer treatments like chemotherapy and radiation
Additional factors that can cause infertility in men
Researchers estimate that about 40% to 50% of the time, the root factor is a cause of infertility in the male, alone.
Where “male factors are often related to varicoceles or trauma that affects sperm production in the testes,” says George.
For men, the key factors in determining fertility are both the quality and quantity of your sperm. High-quality sperm is often associated with high motility, which is a sperm’s ability to swim through the vagina, up the cervix, and into the fallopian tubes where it can fertilize an egg. If you have weak sperm, you’re less likely to impregnate a woman. Quantity – or how many sperm are in each ejaculation – is also important. The more the better.
There are many different ways to damage the quality and quantity of your sperm, George says. For example, activities and habits that expose your testicles to pressure or heat including:
- Frequent bicycle riding
- Supporting your computer on your lap
- Wearing tight clothing in the groin area
- Frequent time spent in jacuzzis or saunas
Then, there’s your diet and overall mental and physical health. Research has shown that many factors associated with an unhealthy lifestyle are also linked to infertility in men, including:
- A poor diet low in fruits, vegetables, and other fibre-rich foods and high in processed meats, trans fats, and high-fat dairy
- Drinking alcohol
- Smoking– cigarettes or otherwise
- Using anabolic steroids that promote muscle growth
- Obesity and poor fitness
- Chronic psychological stress
- Insufficient sleep
- Jet lag, working night shifts, or other disruptions to your circadian rhythm
Medications can also inhibit male infertility. According to the CDC, below are some examples of such medications.
- Prostate cancer medications
- Spironolactone, a blood pressure medication
- Anti-fungal medicine like ketoconazole
- Cimetidine, which is used to treat heartburn and stomach ulcers
- For the complete list of medications, visit the CDC.
There are also certain medical conditions that affect male infertility including:
- Varicoceles, which is when the vein in your scrotum is larger than normal, which can reduce sperm quantity.
- Infections or tumours of the reproductive organs such as epididymitis, which occurs when the tube that carries your sperm becomes inflamed.
- Cryptorchidism is when your testicles don’t fully descend, which can affect sperm production
- Hormonal imbalances such as low luteinizing and follicle-stimulating hormones, which are key in your production of testosterone and sperm
- Celiac disease
- Chromosome defects, which can cause a chemical pregnancy and lead to miscarriage.
Lastly, some research suggests that certain environmental chemicals – like BPA and phthalates – and pollution – like the air pollutants sulphur dioxide and carbon monoxide – can cause infertility in both men and women. Though, more research is needed to understand exactly how these factors play a role in overall reproductive health.
Additional factors that can cause infertility in women
There are many reasons for why a woman may not ovulate, but the most common reason related to infertility is polycystic ovary syndrome or PCOS. PCOS is when women produce more androgen, or male, hormones than normal, which can prevent ovulation as a result. PCOS accounts for an estimated 80% of infertility cases associated with a lack of ovulation.
Age can also play a role in infertility. “Women over 32 years old are more likely to have problems ovulating, especially the longer they wait to become pregnant,” George says.
Additionally, just like for men, physical and mental health play an important role in a woman’s ability to conceive. Below are some examples:
- Poor diet. Research indicates that a diet high in saturated fats and sugar is linked to infertility issues in women.
- Chronic stress. It’s unclear whether stress causes infertility, but researchers have found that pregnancy rates increased in women who reduced their stress levels.
- Poor sleep or disruptions to your circadian rhythm, like working night shifts, has been shown to affect the production of certain key reproductive hormones like TSH (thyroid-stimulating hormone) and prolactin.
Medical conditions that affect female infertility include:
- Endometriosis, which occurs when lesions grow on the outside of the uterus and can cause severe pain during menstruation. An estimated 30% to 50% of women with endometriosis experience infertility.
- Fallopian tube scar tissue, from STD-related pelvic inflammatory disease or endometriosis.
- Infections in the vagina or cervix, such as HPV and untreated STIs like gonorrhea and chlamydia can make it difficult for sperm to survive.
- Diminished egg reserve, which can happen as you get older – especially in your late ’30s and ’40s.
- Functional amenorrhea (loss of the menstrual cycle), due to excessive exercise, low body weight, or anorexia.
- Structural abnormalities in the uterus such as blocked tubes or intrauterine growths.
- Celiac disease
- Thyroid disease
There are more factors that can contribute to infertility in women. Check out the CDC for more information.
When to see a fertility specialist
For couples who are actively trying to get pregnant, 80% to 90% are able to conceive in the first year, and 95% will get pregnant within two years.
If you have not been able to conceive after six months of actively trying, particularly if you are 35 years of age or older, you should consider scheduling an appointment with a doctor or specialist since it could be a sign of infertility.
George also says that it’s common for a couple to not even realise if fertilisation occurred because the pregnancy is lost before the next menstrual cycle starts.
“In our practice, we encourage couples to reach out to us if unable to conceive after six months of actively trying to conceive,” George says. “We are able to start some conservative testing to rule out causes that may be treatable with a little hormonal support, lifestyle change, or even an antibiotic.”
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