What really causes infertility? Learn 18 causes of female infertility and 9 causes of male infertility, including diet and lifestyle factors that are rarely discussed, but are hugely important for reproductive health!
Note from Dena: This post was written by Sarah Kaufman, Dietetic Intern, as part of a research partnership between Back To The Book Nutrition and post-graduate nutrition students from the University of Houston.
In the U.S., more and more women are waiting longer to try to have babies. Many of us already know age is one of the main factors influencing a woman’s ability to have a baby, but there are also other factors that can affect fertility including hormonal imbalances, obesity, and thyroid disorders... just to name a few.
While infertility is usually thought of as a woman’s disorder, this is a common misconception. One third of infertility is attributed to women, another third to men, and a final third is thought to be caused by a combination of problems in both partners. Looking for causes of male infertility? Scroll down!
What Really Causes Infertility?
18 Female Infertility Causes
1. Not Ovulating
In order to get pregnant a woman needs functioning ovaries, fallopian tubes, and a uterus. If any of these organs aren’t working properly it can lead to infertility.
Anovulation is when ovulation doesn’t take place. It’s important to note that a woman can bleed during her monthly period and NOT be ovulating. In fact, recent research showed that approximately 1/3 of the time, a woman who has “normal” monthly periods doesn’t ovulate. (5) If a woman has frequent anovulation, this can lead to infertility.
Reasons for anovulation:
- Polycystic ovarian syndrome (PCOS) is a leading cause of infertility and may be caused by an abnormal interaction between insulin and luteinizing hormone (LH). Women with PCOS have a normal number of eggs, but their eggs do not mature the way they are supposed to. Learn more about PCOS here (link to PCOS article)
- Diminished ovarian reserves (DOR) occurs when there are fewer eggs in the ovaries than normal.
- Functional hypothalamic amenorrhea (FHA) is caused by excessive exercise, stress, undereating in general or undereating of carbohydrates, or low body weight, and can be linked with eating disorders such as anorexia which can cause periods to stop.
- Improper function of the hypothalamus and pituitary glands – Normal function of the ovaries is controlled by hormones produced by the hypothalamus and pituitary glands. When too much prolactin hormone (used to help women produce milk after childbirth) is produced it may cause a woman to not ovulate leading to infertility.
- Premature ovarian insufficiency (POI) or premature menopause is when a woman’s ovaries fail before the age of 40. Chemotherapy or pelvic radiation may cause POI.
- Perimenopause/Menopause that cause a decline in ovarian function usually beginning around age 45-50.
- Nutrition and Lifestyle Factors outlined in greater detail below.
2. Fallopian Tube Obstruction
Fallopian tube obstruction – or tubal occlusion – is when an egg is unable to reach the uterus and sperm cannot reach the egg preventing the egg from being fertilized. A common cause of tubal occlusion is a history of gonorrhea or chlamydia.
3. Uterine Abnormalities
The uterus(womb) should be evaluated as part of a routine infertility investigation checking for polyps, fibroids, and structural abnormalities. (1)
Egg supply declines with age and aging also affects the quality of eggs. Hormones may also be affected by aging leading to difficulty conceiving.
- By age 35 – significant decrease in fertility
- By age 40 – 50% lower fertility
5. Imbalances in the Vaginal Microbiome
The vaginal microbiome – the balance of “good” and “bad” bacteria in the vagina – plays a key role in balancing the bacteria in conception and healthy pregnancy outcome.
Vaginal yeast infections, bacterial baginosis (BV), Pelvic Inflammatory Disesase (PID), and sexually transmitted diseases (STDs) are all signs of imbalance in the vaginal microbiome and have been linked to reduced fertility and poorer pregnancy outcomes such as low birth weight and miscarriage. (6) If these are recurrent, it’s very likely they stem from bacterial imbalances in the gut microbiome, and testing and addressing the gut imbalance may be necessary to fully overcome the vaginal imbalance.
Polycystic Ovarian Syndrome (PCOS) is believed to be the most common causes of female infertility. Contrary to the conventional medical approach to suppressing PCOS symptoms (i.e., putting a woman on the pill, which we know does nothing to repair the root cause of the condition and can lead to serious side effects), this condition is highly responsive to diet, supplements, and lifestyle approaches.
Endometriosis is a disorder in which tissue that normally lines the inside of your uterus grows outside your uterus. About 25 to 50% of infertile women have endometriosis, and 30 to 50% of women with endometriosis are infertile.(3)
The inflammation and irritation caused by endometriosis can affect fertility, and in advanced cases can cause adhesions to the pelvic organs resulting in decreased function. Endometriosis can also block the fallopian tubes. Like PCOS, endometriosis is a condition of hormonal imbalance. And, as with PCOS, diet, supplements, and lifestyle measures that help restore balance and decrease inflammation can be extremely helpful for women with endometriosis.
8. Other Hormonal Imbalances
In addition to PCOS and endometriosis, other forms of hormonal imbalance can disrupt ovulation, prevent thickening of the uterine lining, and otherwise prevent pregnancy.
There are a number of reasons your hormones can be out of balance, including:
- Estrogen dominance/excess and/or low progesterone levels
- Poor diet (more details below)
- Nutrient deficiencies
- Unhealthy habits and unbalanced lifestyle
- Use of cosmetics and personal care products with hormone disrupting ingredients
- Use of non-organic animal products
- Hormonal birth control
- Thyroid issues
- Lack of exercise
- Cigarette smoking
- Alcohol use
9. Thyroid Dysfunction
Thyroid dysfunction – whether hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid) – can decrease or stop ovulation completely, and can also cause a short luteal phase. The luteal phase is the time period that immediately follows ovulation. If your luteal phase is too short, a fertilized embryo may not be able to implant.
Also, women with autoimmune thyroid diseases like Graves Disease and Hashimoto’s Thyroiditis have approximately 50% lower fertility rates than healthy women. Miscarriage rates are also higher with these conditions. (2,8)
10. Unhealthy Diet
The Standard American Diet (appropriately abbreviated, “SAD”) poses many challenges to fertility. (10)
Dietary Factors Linked to Infertility:
- Trans fat intake (trans fats are common in restaurant and fast foods and are listed as hydrogenated”, “partially hydrogenated,” or “interesterified” oils on the ingredient list of packaged foods)
- High intake of sugars/refined carbs
- Low plant food intake
- Low fish intake
- High intake of conventionally raised meats
- Inadequate intake of folate, B vitamins, vitamin C, vitamin E, selenium, and zinc
- Low vitamin D (serum vitamin D <32 ng/mL)
- Low intake of full fat dairy products
- High alcohol intake (4 or more drinks per week)
11. Excess Caffeine Consumption
Studies have shown conflicting results regarding caffeine consumption and infertility. Some studies have shown no relationship between caffeine and the ability to conceive; but, since other research has shown that women who consume about two cups of regular coffee (or five 12-ounce cans of caffeinated soda) have twice the miscarriage risk as those who didn’t have any, most practitioners agree that 200 mg/day is a prudent precaution until more is known.
12. Alcohol Consumption
Alcohol depresses the adrenal glands and slows the release of hormones impairing egg health, and increases risk for Fetal Alcohol Syndrome which can result in defects in baby’s heart, brain, kidneys, or other body systems. (9)
Obesity’s affect on the reproductive system is complex. It can cause hormonal imbalances, inflammation, insulin resistance, and problems with ovulation. Likewise, inflammation, insulin resistance, and hormone imbalance can all make it harder to lose weight, making it a vicious cycle for some women.
14. Low Body Weight
Being too thin can be just as harmful as being overweight. It can cause hormone imbalances that cause anovulation and reduce fertility. Compared to healthy weight women, underweight women are over twice as likely to struggle with infertility, often taking more than a year to get pregnant.
Smoking affects many stages of the reproductive process and increases a woman’s chances of having a miscarriage, ectopic pregnancy (where the fetus develops outside the uterus),
16. Physical and Emotional Stress
Chronic stress may contribute to reproductive disorders by causing an imbalance in hormones like cortisol, insulin, and ghrelin.(4) Because our bodies were designed to prioritize responding to stressful events over things like reproduction, it is nearly impossible to live under chronic stress without suffering some degree of hormone imbalance.
Remember that “stress” includes both emotional stressors (worry, grief, excitement, etc.) as well as physical ones (inflammation, infections, poor sleep, poor blood sugar control, etc.)
17. Environmental Toxins
Hormonal imbalances leading to infertility can result from environmental chemicals such as soft plastics which release toxic chemicals. Plastic products have estrogen-like effects in our bodies. This isn’t just limited to BPA. It includes dioxins, phthalates, lead, and many others that are found nearly everywhere these days – clothing, makeup and personal care products, building materials, and even our water supply. Many of these chemicals have been shown to disrupt hormones and challenge our bodies’ natural detox pathways.
18. Sexually Transmitted Diseases
HPV and other STDs may decrease fertility and lead to poorer pregnancy outcomes such as pre-term labor and miscarriage. (7)
9 Causes of Male Infertility
Contrary to popular belief, male partners are responsible for up to 50% of infertility cases (one-third of cases that are exclusively male issues, plus half of the one-third that are linked to both partners). In order for a man to get his partner pregnant he must produce enough healthy sperm.
Contributors to low sperm count and poor sperm quality (10):
1. Poor diet including trans fat intake, low antioxidant intake, and high intake of processed foods
2. Low vitamin D levels
3. Environmental toxins such as industrial chemicals, heavy metal exposure, radiation or x-rays, and overheating testicals can affect sperm production and function.
4. Significant Obesity (BMI >35) causes hormone changes that reduce male fertility by lowering testosterone levels, increasing the risk of erectile dysfunction, and/or lowering sperm count.
5. Prolonged stress might interfere with hormones needed to produce sperm.
6. Alcohol and smoking – Drinking can lower testosterone levels as well as decrease production of sperm. It has also been proven that men who smoke can have a lower sperm count than those who don’t.
7. Using drugs like anabolic steroids can cause the testicles to shrink and sperm production to decrease. Using cocaine or marijuana might reduce the number and quality of your sperm as well.
8. Occupations associated with prolonged sitting may be linked to risk for infertility, but studies are still being done.
9. Sexually transmitted diseases can decrease the health of the sperm.
How to increase fertility naturally
About the Author
Sarah Kaufman is a Dietetic Intern at the University of Houston. She graduated with a B.S. in Human Nutrition and Dietetics at Metropolitan State University of Denver. Through her own personal struggles with nutrition she developed a passion for helping others find a balanced lifestyle in order to achieve great health.
Disclaimer: Information on this site is intended only for informational purposes and is not a substitute for medical advice. Always consult with a trusted healthcare provider before implementing significant dietary change. Read additional disclaimer info here.
1. Centers for Disease Control. Infertility FAQs. Accessed: https://www.cdc.gov/reproductivehealth/infertility/index.htm
2. WebMD. Thyroid Trouble May Harm Women’s Fertility: https://www.webmd.com/infertility-and-reproduction/news/20150126/thyroid-trouble-may-harm-womens-fertility-study-finds#1
3. Bulletti, et al. Endometriosis and infertility. J Assist Reprod Genet. 2010 Aug; 27(8): 441–447. Accessed: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941592/
4. Sominsky, L., et al. Ghrelin – a novel link between stress and infertility. Brain, Behavior, and Immunity. 2017 Nov; 66(Supplement):e22. Accessed: https://www.sciencedirect.com/science/article/pii/S0889159117303124
5. Prior, J.C., et al. Ovulation Prevalence in Women with Spontaneous Normal-Length Menstrual Cycles – A Population-Based Cohort from HUNT3, Norway. PLoS One. 2015; 10(8): e0134473. Accessed: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4546331/
6. Freitas, A.C., et al. The vaginal microbiome of pregnant women is less rich and diverse, with lower prevalence of Mollicutes, compared to non-pregnant women. Scientific Reports. 2017; 7: Article number: 9212. Accessed: https://www.nature.com/articles/s41598-017-07790-9
7. Pereira N, Kucharczyk KM, Estes JL, et al. Human Papillomavirus Infection, Infertility, and Assisted Reproductive Outcomes. Journal of Pathogens. 2015;2015:578423. Accessed: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4644557/
8. Quintino-Moro, A., et al. High Prevalence of Infertility among Women with Graves’ Disease and Hashimoto’s Thyroiditis. International Journal of Endocrinology. 2017; Article ID 982705. Accessed: https://www.hindawi.com/journals/ije/2014/982705/
9. Mayo Clinic. Fetal Alcohol Syndrome. Accessed: https://www.mayoclinic.org/diseases-conditions/fetal-alcohol-syndrome/symptoms-causes/syc-20352901
10. Collins, G.G. and Rossi, B.V. “The impact of lifestyle modifications, diet, and vitamin supplementation on natural fertility.” Fertility Research and Practice 2015;1:11.