Lifestyle Factors That Actually Affect Fertility: Evidence-Based Guidance

If you have spent any time researching fertility, you have probably encountered an overwhelming amount of lifestyle advice. Cut out coffee. Eat organic. Try this supplement. Avoid that exercise. Stand on your head after sex. Okay, maybe not that last one, but it can start to feel equally absurd.

The frustrating reality is that much fertility advice floating around online is either unsupported by evidence, exaggerated from small studies, or simply made up. Meanwhile, the factors that genuinely matter often get lost in the noise.

This guide cuts through the clutter. We will focus on lifestyle factors that research actually supports, be honest about what the evidence shows (and does not show), and help you prioritise changes that make a real difference rather than chasing every possible optimisation. Because you have enough to worry about without wondering whether your morning latte is ruining your chances. To understand how these factors fit into the bigger picture, explore our Understanding Fertility guide.

The Honest Truth About Lifestyle and Fertility

Before diving into specifics, let us set realistic expectations.

What Lifestyle Can and Cannot Do

Lifestyle factors matter. Certain choices genuinely affect your fertility, for better or worse. Optimising these factors can improve your chances of conception and support a healthy pregnancy.

Lifestyle is not usually the whole story. Most fertility challenges have causes beyond lifestyle. If you have blocked tubes, perfect nutrition will not open them. If sperm count is severely low, avoiding hot tubs will not solve it. Lifestyle optimisation supplements medical treatment; it rarely replaces it.

Perfection is not required. Healthy, fertile people conceive every day while drinking coffee, eating non-organic food, and exercising imperfectly. The goal is reasonable optimisation, not obsessive control.

The Role of Stress

A quick word on stress, since it comes up constantly in fertility discussions. Yes, chronic severe stress can affect hormones and potentially fertility. But the relationship is complicated, and telling someone "just relax" is unhelpful and often hurtful.

More importantly: the stress of trying to conceive is real and valid. Feeling anxious does not mean you are sabotaging your chances. Research does not support the idea that normal levels of stress prevent pregnancy. What stress does affect is your wellbeing during an already difficult time, which is reason enough to manage it, but not because it is "blocking" your fertility.

Factors That Genuinely Matter

These are the lifestyle factors with solid evidence behind them.

Body Weight

Weight affects fertility through hormones, inflammation, and metabolic function. Both significantly low and significantly high body weight can impair fertility.

Being underweight:

• Can stop ovulation entirely (hypothalamic amenorrhea)
• May affect sperm production in men

Being overweight or obese:

• Disrupts hormone balance, particularly in PCOS (now also called PMOS)
• Associated with irregular ovulation
• Linked to taking longer to conceive
• Linked to reduced fertility in men

What the research shows: NICE advises that women with a BMI of 30 or more are likely to take longer to conceive, and that men with a BMI of 30 or more have an increased risk of reduced fertility. For women with a BMI under 18.5 who have irregular or absent periods, gaining weight is likely to improve the chance of conceiving.

Practical approach:

• If you have a BMI of 30 or more and aren't ovulating, losing weight is likely to improve your chances, and a group programme combining exercise and dietary advice leads to more pregnancies than weight-loss advice alone
• If underweight, gaining weight to support normal menstrual function is important
• Extreme dieting while trying to conceive is counterproductive
• Focus on sustainable, healthy eating rather than crash diets

Smoking

This one is straightforward: smoking significantly harms fertility in both women and men.

For women:

• Accelerates egg loss (menopause comes 1-4 years earlier in smokers)
• Lowers IVF success: smokers need nearly twice as many IVF attempts to conceive as non-smokers
• Increases miscarriage risk
• Passive smoking is also likely to affect your chance of conceiving

For men:

• Associated with lower sperm count, motility and morphology, and more DNA damage in sperm (although how much this affects male fertility is less certain)
• Associated with erectile dysfunction

What the research shows: The evidence that smoking harms female fertility is strong and consistent, and there is no known "safe" level.

Practical approach: Stop smoking entirely. This is the single most impactful lifestyle change a smoker can make for fertility. Support is available through healthcare providers, quitlines, and various cessation programs.

Alcohol

The evidence on alcohol is more nuanced than on smoking, but the overall picture suggests caution.

For women:

• Heavy drinking clearly impairs fertility and increases miscarriage risk
• Moderate drinking (1-2 drinks per day) is associated with reduced fertility in some studies, though not all
• Any alcohol during pregnancy carries risks to the developing baby

For men:

• Heavy drinking reduces testosterone and sperm quality
• Moderate drinking has less clear effects

What the research shows: Heavy drinking is definitely harmful. The effects of light to moderate drinking are less certain. NICE advises women trying to conceive that, in line with UK Chief Medical Officer guidance, the safest approach is to avoid alcohol altogether. For men, NICE says drinking within 14 units a week, spread over several days, is unlikely to affect semen quality.

Practical approach:

• Ideally avoid alcohol while actively trying
• No alcohol during pregnancy (once you might be pregnant)
• For men, staying within low-risk limits and avoiding binge drinking is reasonable

Recreational Drugs

Most recreational drugs negatively affect fertility.

Cannabis/marijuana:

• Has been linked to changes in reproductive hormones and cycle length in women
• Has been linked to abnormal sperm shape in men
• The overall evidence on fertility is incomplete and conflicting, so it can't be assumed to be safe

Anabolic steroids and testosterone:

• Taking anabolic steroids or testosterone suppresses the body's own sperm production and interferes with fertility while they are being used
• Recovery after stopping can take time

What the research shows: There is no recreational drug that benefits fertility. NICE advises doctors to ask about recreational drugs such as cannabis and anabolic steroids, as well as prescribed and over-the-counter medicines, when someone is trying to conceive.

Practical approach: Stop all recreational drugs when trying to conceive. If you are using anabolic steroids or testosterone, speak with your doctor about stopping, as this needs managing.

Caffeine

Caffeine is one of the most debated lifestyle factors, and the evidence is mixed.

What studies show:

• NICE's 2026 review found no consistent evidence linking caffeinated drinks (tea, coffee, energy drinks and colas) to fertility problems
• Once you are pregnant, too much caffeine has been linked to a higher chance of miscarriage and stillbirth, which is why the NHS recommends no more than 200mg a day in pregnancy

Practical approach:

• Keeping to under 200mg a day while trying is a reasonable precaution, so you're already within the pregnancy limit (a mug of instant coffee has about 100mg; filter and coffee-shop coffee can contain more)
• You do not need to eliminate caffeine entirely
• Tea, chocolate, and some medications also contain caffeine

Heat Exposure (for Men)

Testicles hang outside the body because sperm production works best slightly below body temperature. Higher scrotal temperature is associated with poorer semen quality.

Sources of heat exposure:

• Frequent sauna or hot tub use
• Hot baths
• Tight underwear
• Laptops placed directly on the lap
• Occupational heat exposure
• Prolonged sitting (truck drivers, desk workers)

What the research shows: The association between heat and poorer semen quality is real, but NICE notes it is uncertain whether simple changes such as looser underwear actually improve fertility. Because sperm take around two to three months to develop, any benefit from reducing heat exposure would take a few months to show.

Practical approach:

• Switch to loose-fitting underwear
• Avoid saunas and hot tubs while trying to conceive
• Keep laptops on a desk or use a barrier
• Take breaks from prolonged sitting

Factors with Less Clear Evidence

Some commonly discussed factors have weaker or mixed evidence.

Exercise

Exercise is generally beneficial for fertility when moderate. The picture becomes complicated at extremes.

Moderate exercise: Beneficial for weight management, hormone balance, stress reduction, and overall health. Associated with better fertility outcomes.

Excessive exercise: Very intense training, particularly combined with low body fat, can disrupt ovulation. This is more common in elite athletes than recreational exercisers.

Lack of exercise: Sedentary lifestyle contributes to weight gain and metabolic issues that can affect fertility.

Practical approach:

• Regular moderate exercise is beneficial
• If you are training intensely and have irregular periods, consider reducing intensity
• If you are sedentary, increasing activity level helps overall health and may support fertility

Diet Quality

Overall diet quality likely matters more than any single food or nutrient.

What studies suggest:

• Mediterranean-style diets (rich in fruits, vegetables, whole grains, fish, olive oil) are associated with better fertility outcomes in several studies
• High intake of processed foods, trans fats, and sugar is associated with poorer fertility
• No single "superfood" has been proven to boost fertility

Practical approach:

• Focus on overall diet quality rather than specific foods
• A diet rich in whole foods, vegetables, lean protein, and healthy fats is reasonable
• Extreme restriction or elimination diets are not necessary unless you have specific medical reasons

Supplements

The supplement industry makes many fertility claims, most unsupported by good evidence.

What has some evidence:

• Folic acid: Strongly recommended for preventing neural tube defects such as spina bifida. All women trying to conceive should take it.
• Vitamin D: Deficiency is common and may affect fertility. Testing and supplementing if deficient is reasonable.
• Coenzyme Q10: Some evidence it may improve egg quality in older women. Not definitive.
• Omega-3 fatty acids: Generally beneficial for health; fertility-specific evidence is limited.

What lacks good evidence:

• Most "fertility blends" and proprietary formulas
• High-dose antioxidant supplements
• Many herbs marketed for fertility

Practical approach:

• Take folic acid (400 micrograms daily, ideally from 3 months before trying until 12 weeks of pregnancy; some women need a higher dose, so ask your doctor)
• Consider a general prenatal vitamin
• Get vitamin D tested and supplement if deficient
• Be sceptical of expensive fertility supplements with bold claims

Environmental Toxins

There is growing concern about environmental chemicals affecting fertility, though the evidence is still developing.

Chemicals of concern:

• BPA (found in some plastics)
• Phthalates (found in plastics and personal care products)
• Pesticides
• Heavy metals

What the research shows: Some studies show associations between exposure and reduced fertility, but it is difficult to prove causation or determine safe levels.

Practical approach:

• Reasonable precautions (reducing plastic use, washing produce, avoiding heavily processed foods) may help
• Obsessing over every possible exposure is neither practical nor clearly beneficial
• The evidence is not strong enough to justify extreme lifestyle changes

What Does Not Matter (Despite What You May Have Heard)

Some commonly shared advice has no scientific support.

Position After Sex

There is no good evidence that lying down after sex, elevating your hips, or any particular position improves conception chances. Sperm move into the cervical mucus quickly after ejaculation; gravity is not going to stop them.

Organic vs. Conventional Food

While reducing pesticide exposure is a reasonable goal, there is no evidence that eating exclusively organic food improves fertility. The benefit of eating more fruits and vegetables likely outweighs concerns about how they were grown.

"Detoxing"

Your liver and kidneys detox your body continuously. Juice cleanses, detox teas, and similar products have no fertility benefit and may actually be harmful if they restrict nutrition.

Specific "Fertility Foods"

Pineapple core, Brazil nuts, pomegranate juice, and countless other foods have been promoted as fertility boosters. None have robust evidence supporting specific fertility effects. Eating a variety of nutritious foods is what matters.

Creating a Sustainable Approach

The goal is not perfection. It is making reasonable choices without adding unnecessary stress.

Priorities

Focus first on factors with the strongest evidence:

1. Stop smoking (if applicable)
2. Achieve or maintain a healthy weight
3. Reduce or eliminate alcohol
4. Stop recreational drugs

Then address secondary factors:

5. Moderate caffeine intake
6. Reduce heat exposure (for men)
7. Exercise moderately
8. Eat a balanced diet
9. Take folic acid and prenatal vitamins

Give Yourself Grace

Making lifestyle changes while dealing with fertility challenges is hard. Some days you will make perfect choices; other days you will need that second cup of coffee or skip the gym. That is okay.

One glass of wine will not ruin your chances. A week of imperfect eating will not undo months of healthy choices. Fertility is influenced by many factors, and lifestyle is just one piece.

Key Takeaways

• Smoking is the most harmful lifestyle factor for fertility. Quitting entirely is the most impactful change a smoker can make.

• Weight matters. Both significantly over and underweight affect fertility. Modest changes can make a real difference.

• Alcohol should be minimised while trying to conceive and eliminated during pregnancy.

• Moderate exercise and healthy eating support fertility without requiring perfection or extremes.

• Many popular fertility tips lack evidence. Focus on what research actually supports, not internet folklore.

• Lifestyle optimisation helps but is not everything. Do not blame yourself if conception does not happen despite perfect choices.

Sources

• NICE NG257: Fertility problems: assessment and treatment (March 2026) (checked October 2026)
• ASRM: Tobacco or marijuana use and infertility, a committee opinion (2024) (checked October 2026)
• AUA/ASRM: Diagnosis and treatment of infertility in men (2020, amended 2024, PDF) (checked October 2026)
• NHS: Foods to avoid in pregnancy (caffeine) (checked October 2026)
• NHS: Vitamins and supplements in pregnancy (checked October 2026)
• NHS: Folic acid, pregnancy and fertility (checked October 2026)
• Suarez and Pacey. Sperm transport in the female reproductive tract. Hum Reprod Update 2006 (checked October 2026)
• Misell et al. A stable isotope method for measuring human spermatogenesis kinetics. J Urol 2006 (checked October 2026)

This content is for educational purposes only and should not replace professional medical advice. Discuss significant lifestyle changes with your healthcare provider.