Tobacco, obesity and some chemical substances influence fertility

According to the World Health Organization (WHO), infertility is defined as the failure to achieve a pregnancy after 12 months or more of regular, unprotected sexual intercourse; for women older than 35 years, evaluation is generally recommended after six months (WHO) [World Health Organization]. Globally, an estimated 48 million couples and 186 million individuals experience infertility, representing a substantial public-health concern with medical, social and economic implications (WHO). Infertility is a multifactorial condition: biological, lifestyle, environmental and iatrogenic factors all contribute to impaired reproductive potential in women and men.

This review summarizes current evidence regarding key modifiable influences on fertility — notably tobacco use, obesity and chemical exposures — and describes clinical approaches to evaluation and management, including recent advances in ovulation induction and assisted reproduction. Sources include professional guidance and public-health resources from the American College of Obstetricians and Gynecologists (ACOG), the U.S. National Institutes of Health (NIH), Mayo Clinic and the Cleveland Clinic.

(References: WHO; ACOG; NIH/NIEHS; Mayo Clinic; Cleveland Clinic)

Overview: causes of infertility

Infertility has two broad categories:

  • Female-factor infertility: ovulatory dysfunction, tubal disease, uterine or cervical abnormalities, diminished ovarian reserve, endometriosis, and other systemic or endocrine disorders.
  • Male-factor infertility: disorders of sperm production or function (count, motility, morphology), ejaculatory dysfunction, or obstructive lesions.

In approximately 25–35% of couples the primary cause is female-factor, 25–35% is male-factor, 15–20% is combined, and 10–15% is unexplained after standard evaluation (ACOG; Mayo Clinic). Many of the determinants of reproductive function are modifiable. Lifestyle factors (tobacco, excess weight, alcohol and drug use, physical inactivity), environmental exposures (pesticides, heavy metals, endocrine-disrupting chemicals), and medical treatments (chemotherapy, pelvic surgery) are all implicated in reduced fecundity.

How lifestyle influences fertility

Lifestyle factors alter reproductive physiology through endocrine, metabolic, vascular and genetic/epigenetic mechanisms. Counseling about modifiable risks is a core component of preconception care.

Tobacco and fertility

Tobacco smoking — both active and passive exposure — negatively affects both female and male fertility.

Female effects

  • Smoking accelerates ovarian follicle depletion and is associated with earlier menopause (by an average of 1–4 years) and diminished ovarian reserve markers (e.g., lower anti‑Müllerian hormone [AMH]) [ACOG; Mayo Clinic].
  • Smoking is linked to reduced oocyte (egg) quality, higher rates of aneuploidy, and increased risk of infertility and miscarriage. In assisted reproduction, smokers have lower success rates with in vitro fertilization (IVF) and greater likelihood of ovarian stimulation failure.
  • Smoking increases ectopic pregnancy risk and may impair tubal motility and endometrial receptivity.

Male effects

  • Active smoking is associated with reduced sperm concentration, motility and morphology, and increased sperm DNA fragmentation, which can reduce fertility and increase adverse reproductive outcomes [Mayo Clinic; NIH].
  • Passive smoking may also have deleterious effects.

Clinical implications

  • Smoking cessation improves reproductive outcomes; preconception cessation is strongly recommended for both partners (ACOG; Mayo Clinic). Even brief abstinence is beneficial, but complete cessation before conception confers greatest effect.

(References: ACOG patient resources; Mayo Clinic – Infertility and Smoking; NIH/NICHD research summaries)

Obesity and reproductive function

Obesity is a leading modifiable risk factor for infertility in high-income and many middle-income settings.

Female effects

  • Excess adiposity disrupts normal hypothalamic–pituitary–ovarian (HPO) axis function: adipose tissue increases aromatase activity and insulin resistance, which can lead to chronic anovulation, polycystic ovary syndrome (PCOS)-like phenotypes, menstrual irregularities and reduced conception rates.
  • Obesity is associated with lower IVF pregnancy and live birth rates, higher miscarriage rates, and greater obstetric and perinatal complications (gestational diabetes, hypertensive disorders, macrosomia) (Cleveland Clinic; ACOG).
  • Obesity can alter oocyte quality and endometrial receptivity.

Male effects

  • Obesity in men is associated with lower testosterone, higher estrogen, decreased sperm count and motility, and increased scrotal temperature, all of which can impair spermatogenesis.

Clinical implications

  • Weight reduction through diet, physical activity and behavioral interventions improves ovulatory function and increases spontaneous conception rates in many women with obesity; even modest weight loss (5–10% of body weight) can restore ovulation in some patients (Cleveland Clinic; ACOG).
  • For couples undergoing ART, many centers recommend weight optimization prior to treatment to improve success and reduce maternal risks.

(References: Cleveland Clinic – How weight affects fertility; ACOG guidance on obesity and reproductive health)

Alcohol, recreational drugs and caffeine

  • Alcohol: Excessive alcohol use is linked to ovulatory dysfunction and decreased fecundity; heavy drinking also negatively affects semen quality in men. Moderate consumption has variable evidence, but most guidelines advise limiting or avoiding alcohol when attempting conception [Mayo Clinic; NIH].
  • Recreational drugs: Cannabis, cocaine and other illicit substances are associated with impaired fertility through endocrine disruption, altered ovulation, reduced sperm parameters and risk behaviors. Abstinence is advised when attempting conception.
  • Caffeine: Evidence is mixed; high caffeine intake (e.g., >300–500 mg/day) has been associated with modestly reduced fertility and may increase miscarriage risk in some studies. Moderate intake (<200–300 mg/day) is generally considered acceptable, but individualized counseling is recommended (Mayo Clinic).

(References: Mayo Clinic – Infertility; NIH resources on substance use and reproduction)

Stress, sleep and physical activity

  • Psychological stress may affect hypothalamic regulation of gonadotropin‑releasing hormone, contributing to cycle irregularity and subfertility. While evidence is complex and bidirectional, stress-management interventions may improve quality of life and potentially reproductive outcomes.
  • Both insufficient and excessive physical activity can affect fertility. Extremely vigorous exercise, especially in the setting of low energy availability, can cause hypothalamic amenorrhea. Conversely, regular moderate exercise supports metabolic health and may improve outcomes for overweight individuals (ACOG; Mayo Clinic).

(References: ACOG; Mayo Clinic)

Chemical and environmental exposures that influence fertility

A growing body of research implicates environmental chemical exposures — especially endocrine-disrupting chemicals (EDCs) — in adverse reproductive outcomes. The U.S. National Institute of Environmental Health Sciences (NIEHS/NIH) provides consumer and professional resources on endocrine disruptors and reproductive health.

Endocrine disruptors: BPA, phthalates and parabens

  • Bisphenol A (BPA), phthalates and parabens are common components of plastics, personal care products and food packaging. These compounds can mimic or interfere with endogenous hormones, altering steroidogenesis, folliculogenesis and sperm production.
  • Epidemiologic studies have associated higher urinary concentrations of some phthalate metabolites and BPA with decreased semen quality in men, lower ovarian reserve metrics in women, impaired embryo quality, and reduced IVF success rates. Mechanistically, EDCs may induce oxidative stress, epigenetic changes and altered receptor signaling (NIH/NIEHS).
  • Clinical recommendations include minimizing avoidable exposures: using phthalate/BPA‑free food containers, avoiding heating food in plastic, reducing use of certain personal-care products, and limiting consumption of highly processed canned foods.

(Reference: NIH/NIEHS – Endocrine Disruptors and Reproductive Health)

Pesticides, herbicides and occupational exposures

  • Agricultural chemicals, certain industrial solvents, and occupational exposures (e.g., lead, cadmium, benzene, certain hydrocarbons) are associated with subfertility, altered menstrual cycles, reduced sperm parameters and increased risk of miscarriage.
  • Healthcare providers should inquire about occupational and hobby exposures (agriculture, manufacturing, painting, solvent use) and advise protective measures or temporary work reassignment when appropriate.

(References: NIH/NIEHS; Mayo Clinic)

Heavy metals and air pollution

  • Lead and cadmium exposures are associated with reduced sperm concentration and motility in men and menstrual disturbances in women. Mercury exposure can affect neurodevelopment and is particularly important to avoid during pregnancy.
  • Ambient air pollution (fine particulate matter, nitrogen oxides) has been associated in some studies with reduced fecundability and adverse pregnancy outcomes. Reducing exposure where feasible — e.g., indoor air quality improvements, avoiding heavy-traffic commuting when possible — is reasonable preconception advice.

(References: NIH; WHO environmental health resources)

Medical conditions and medications that affect fertility

Several chronic medical disorders and some medications have direct or indirect effects on reproductive function.

  • Endocrine disorders: uncontrolled thyroid disease and hyperprolactinemia can cause amenorrhea, anovulation and infertility; appropriate diagnosis and treatment often restore fertility (ACOG).
  • Metabolic conditions: poorly controlled diabetes impairs fertility and increases obstetric risks; preconception glycemic optimization reduces maternal and fetal complications.
  • Autoimmune and systemic conditions: disorders such as systemic lupus erythematosus and inflammatory bowel disease can affect fertility through disease activity, medication effects or pelvic inflammation.
  • Chemotherapy and radiation: cytotoxic therapies can cause temporary or permanent gonadal failure; fertility preservation (oocyte or embryo cryopreservation, sperm banking, ovarian suppression) should be discussed before therapy when feasible.
  • Medications: certain drugs (e.g., some psychotropics, anabolic steroids, long-term opioids, chemotherapy agents) can impair fertility. Patients should review medication risks and alternatives with their clinician prior to conception attempts.

(References: ACOG; NIH; Mayo Clinic)

Age and ovarian reserve

Reproductive potential declines with age, particularly for women. Ovarian reserve — the quantity and quality of remaining oocytes — diminishes progressively, with accelerated decline after the mid‑30s. Age-related increases in aneuploidy contribute to reduced fecundity and higher miscarriage rates. Assessment of ovarian reserve commonly includes measurement of AMH, antral follicle count (ultrasound) and baseline FSH levels; these tests guide counseling and selection of fertility treatment strategies (ACOG; Mayo Clinic).

(References: ACOG – Ovarian Reserve Testing; Mayo Clinic)

Clinical evaluation of the infertile couple

A structured diagnostic approach identifies potentially correctable causes and optimizes individualized treatment.

Initial evaluation

  • Timing: After 12 months of unprotected intercourse for women under 35, or after 6 months for women 35 and older.
  • History and physical: Detailed reproductive, sexual, menstrual, obstetric, medical, surgical, family, environmental and occupational history; medication, substance use and lifestyle factors; focused pelvic and general physical exam.
  • Semen analysis: at least one assessment of volume, concentration, motility and morphology according to laboratory standards.
  • Ovulation assessment: menstrual history, mid‑luteal progesterone, and/or documented ovulation by basal body temperature, ovulation predictor kits, or serum progesterone.
  • Ovarian reserve testing: AMH and antral follicle count for women with risk factors or advanced reproductive age.
  • Tubal evaluation: hysterosalpingography (HSG) or sonohysterography to assess tubal patency and uterine cavity; hysteroscopy/laparoscopy as indicated.
  • Additional testing: endocrine evaluation (TSH, prolactin), infection screening, genetic testing when indicated.

(References: ACOG Practice Bulletins; Mayo Clinic – Infertility evaluation)

Treatment options and advances in ovulation induction

Management is individualized based on etiology, duration of infertility, age and couple preferences. Interventions range from lifestyle modification and pharmacotherapy to intrauterine insemination (IUI) and assisted reproductive technologies (ART).

Lifestyle and medical management

  • Smoking cessation, weight optimization, alcohol and substance abstinence, and occupational/environmental exposure reduction are first-line interventions.
  • Treat underlying medical conditions (thyroid disease, diabetes, hyperprolactinemia) before ART.
  • Ovulation induction for anovulatory infertility: first-line pharmacologic agents include letrozole (aromatase inhibitor) for women with PCOS and clomiphene citrate in some settings; gonadotropin therapy is used for refractory cases (ACOG; NIH).

Ovulation induction and gonadotropins: recombinant versus urinary products

Advances in assisted reproduction include improved formulations and dosing strategies for gonadotropins (FSH and LH) used to stimulate follicular development.

  • Urinary gonadotropins: extracted and purified from human urine (postmenopausal gonadotropins) have been used for decades; they provide a mix of FSH and LH activity but exhibit batch variability and a theoretical risk of proteinaceous contaminants.
  • Recombinant gonadotropins: produced by recombinant DNA technology, allowing highly purified and consistent preparations of FSH (and LH in some formulations). Recombinant products enable precise dosing, reduced immunogenicity and more predictable pharmacokinetics.
  • Clinical considerations: both types are effective for ovarian stimulation. Choice depends on patient characteristics, prior response, local availability and cost. Efforts to optimize protocols aim to maximize live birth rates while minimizing ovarian hyperstimulation syndrome (OHSS) and multiple pregnancy risk (ACOG; NIH).
  • LH supplementation: in certain subgroups (e.g., older women, poor responders), the addition of recombinant LH to FSH may be considered to improve follicular steroidogenesis and oocyte competence, though evidence varies by population.

(References: ACOG Practice Bulletins on ovulation induction and ART; NIH summary on ART)

Assisted reproductive technologies (ART)

  • IUI is an option for mild male-factor infertility, unexplained infertility or cervical factors, often combined with controlled ovarian stimulation.
  • IVF and intracytoplasmic sperm injection (ICSI) are standard for tubal disease, severe male-factor infertility, advanced maternal age, and other indications. Laboratory techniques (embryo culture, preimplantation genetic testing) and optimized stimulation protocols have improved outcomes.
  • Fertility preservation: oocyte or embryo cryopreservation is an established option for individuals undergoing gonadotoxic therapy or those who wish to defer childbearing.

(References: ACOG; Mayo Clinic – ART and fertility preservation)

Counseling and practical preconception advice

Preconception counseling should address modifiable risks, optimize chronic disease management and review medications.

  • Vaccinations: ensure immunity to rubella and varicella prior to conception; certain live vaccines should be administered preconception.
  • Folic acid: recommend daily folic acid supplementation (400–800 mcg) to reduce neural-tube defect risk.
  • Smoking and substance cessation: provide resources for cessation programs; consider pharmacotherapy under medical supervision if needed.
  • Weight management: individualized weight-loss strategies; refer to nutrition and exercise programs.
  • Environmental risk reduction: practical advice on limiting exposure to plastics with BPA/phthalates, reducing pesticide contact, and minimizing occupational exposures.
  • Medication review: assess teratogenic risk and switch to safer alternatives when possible prior to conception.

(References: ACOG – Preconception care; CDC/NIH resources)

Public-health implications and population-level interventions

Infertility prevention requires population-level strategies addressing tobacco control, obesity prevention, workplace safety, regulation of hazardous chemicals and improved access to fertility care. Clinicians also play a role in public education, advocating for policies that reduce environmental exposures that threaten reproductive health.

Summary and clinical takeaways

  • Infertility affects millions of individuals worldwide. It is multifactorial, and both partners should be evaluated early when pregnancy does not occur within guideline‑recommended timeframes.
  • Modifiable factors with strong evidence for adverse effects on fertility include tobacco use, obesity, excessive alcohol and substance use, and exposures to certain environmental chemicals (EDCs, pesticides, heavy metals). These exposures affect both female and male reproductive physiology.
  • Clinical evaluation includes semen analysis, ovulatory assessment, ovarian reserve testing, and tubal/uterine evaluation. Management integrates lifestyle modification, medical therapy for specific etiologies, and ART when indicated.
  • Advances in ovulation induction and the availability of highly purified recombinant gonadotropins offer improved dosing precision and safety in ART; however, individualized protocol selection remains essential.
  • Preconception counseling and multidisciplinary care — including reproductive endocrinology, occupational health, primary care and mental-health support — optimize the chances of conception and healthy pregnancy outcomes.

Patients or couples concerned about fertility should seek evaluation from a clinician experienced in reproductive medicine. Early identification and modification of risk factors such as tobacco use, excess weight and avoidable chemical exposures can improve reproductive prospects and overall health.

Sources and further reading

  • World Health Organization. Infertility. https://www.who.int/news-room/fact-sheets/detail/infertility
  • American College of Obstetricians and Gynecologists (ACOG). Patient FAQs and Practice Bulletins on infertility and assisted reproductive technology. https://www.acog.org
  • National Institutes of Health / National Institute of Environmental Health Sciences (NIEHS). Endocrine Disruptors. https://www.niehs.nih.gov/health/topics/agents/endocrine/index.cfm
  • Mayo Clinic. Infertility: Overview and causes. https://www.mayoclinic.org/diseases-conditions/infertility/symptoms-causes/syc-20354317
  • Cleveland Clinic. How weight affects fertility. https://health.clevelandclinic.org/how-weight-affects-fertility

(For specific clinical recommendations, refer to primary guideline documents from ACOG, professional societies and local institutional protocols.)