Why Is Fertility Declining in Canada?

The short answer

There is a real fertility problem, but not the simple one the headlines imply.

Canada is having fewer children than it did even a decade ago. The total fertility rate, which estimates the average number of children a woman would have over her lifetime if current birth patterns continued, fell from 1.58 in 2014 to a record low of 1.25 in 2024. That is a decline of approximately 21% in ten years and places Canada well below the population replacement level of approximately 2.1 children per woman. Canadians are also having children later. The average age at childbirth rose from 26.7 in 1976 to 31.8 in 2024.¹ Looking toward 2050, Statistics Canada's current projection scenarios keep fertility below replacement, ranging from 1.09 to 1.55 children per woman, with a medium assumption of 1.32.²

A population's birth rate reflects when people start families, how many children they want, whether they can afford or support them, partnership patterns, access to care, pregnancy loss, and biological capacity.³ Clinical infertility has a different definition: failure to achieve pregnancy after 12 months of regular unprotected intercourse, with earlier evaluation appropriate in several circumstances.^{4, 7}

The most defensible conclusion is more nuanced. People are trying later, when age-related reproductive decline matters more. Common conditions such as PCOS and endometriosis remain underdiagnosed. Metabolic health and some environmental exposures can affect reproduction. Male factors contribute in a substantial share of cases and are too often assessed late. At the same time, evidence is not strong enough to label every low birth rate, hormone change, or chemical exposure as proof of a biological fertility collapse.

Age affects both partners

The biology of delay is real, but it is not symmetrical.

Female age remains the single most important predictor of fecundity. The number of available oocytes falls over time, and age-related changes increase the proportion of eggs with chromosomal errors. This lowers the monthly chance of conception and increases miscarriage risk. The decline is gradual, not a cliff on a birthday, and varies between people. Still, postponing an attempt can narrow both the biological window and the range of treatment options.^{7, 8}

Men also have a biological clock, although there is no menopause-like endpoint and no universally accepted age cutoff. With advancing paternal age, semen volume, motility, and morphology can decline, while sperm DNA fragmentation and new germline mutations tend to rise. Some studies associate older paternal age with lower assisted reproduction success and certain pregnancy or offspring outcomes.^{9, 10}

Risk communication matters. Most children of older fathers are healthy, and the absolute risk of any one rare outcome remains low. Paternal age should be part of counseling and shared planning, not a source of blame or a claim that sperm becomes suddenly unsafe at 40.

Beyond ovarian aging

PCOS, endometriosis, and metabolic health can compound the effect of time.

Other female factors also matter, including tubal damage after infection, fibroids or uterine abnormalities, diminished ovarian reserve, thyroid or prolactin disorders, prior ovarian surgery, and gonadotoxic cancer treatment. A good assessment follows the history rather than assuming every person needs the same panel.

Male fertility is half of the first assessment

Sperm health, sexual function, and testosterone require careful interpretation.

A widely discussed meta-analysis estimated a substantial decline in average sperm concentration and total sperm count among unselected men from 1973 to 2018.¹³ This is a concerning population signal. It is not proof that every man's fertility has halved, that one exposure caused the trend, or that sperm count alone determines pregnancy. A newer study of confirmed fertile men in the United States did not find a clinically meaningful decline over its study period.¹⁴ Differences in populations, collection methods, geography, and study design remain important.

A semen analysis is usually the highest-value first test for a male partner. Results should be interpreted as a pattern, and an abnormal result is often repeated because semen parameters vary. Sperm DNA fragmentation testing can be useful in selected situations, but professional guidelines do not recommend it as routine initial testing. The result does not identify one cause or guarantee that a particular treatment will improve live birth.¹⁰

It is also too simplistic to state that testosterone falls by exactly 1% each year and therefore sperm count falls with it. Hormone trajectories vary with sleep, body composition, chronic illness, medications, and other factors. Low libido, erectile or ejaculatory difficulty can lengthen time to conception and deserve clinical attention, but a serum testosterone value is not a substitute for semen analysis.

Male evaluation should happen at the same time as female evaluation. Sequential care can lose months, reinforce stigma, and miss an immediately actionable factor.

Concern without catastrophizing

Environmental exposures matter. “Detoxing” is not the answer.

Research links some pesticides, solvents, heavy metals, air pollutants, phthalates, bisphenols, and persistent organic pollutants with reproductive or developmental outcomes. Plausible mechanisms include endocrine disruption, oxidative stress, altered cell signaling, and epigenetic change. The evidence is strongest for some occupational or high-dose exposures. For everyday mixtures at typical levels, measuring an individual's exact fertility effect is difficult.^{10, 19}

Animal and experimental studies raise legitimate questions about epigenetic effects across generations. They do not justify telling an individual that ordinary exposure has permanently “rewritten” their sperm or eggs, or that a commercial cleanse can reverse it. “Body burden” describes accumulated chemical exposure; it is not a clinical diagnosis.

These are reasonable exposure-reduction steps, not a promise of improved fertility. Individual action has limits. Product regulation, safer workplaces, pollution control, and better biomonitoring are public-health responsibilities.

The highest-value window

Why preconception planning matters

Preconception care is not a luxury wellness phase. It is the time to find risks that are easier to address before pregnancy, identify when trying without assessment may waste valuable time, and make pregnancy safer if conception occurs quickly.

A visit about three months before trying is practical when possible. It allows time to begin folic acid, review medications and vaccines, improve chronic disease control, address substance use, and evaluate symptoms.^{5, 6} It also spans much of the sperm-development cycle. Three months is a planning window, not a rule to delay conception or fertility referral.

Planning cannot guarantee pregnancy, stop ovarian aging, measure “egg quality,” or cleanse reproductive cells. Its value is better decisions, safer preparation, and earlier access to appropriate care.

A targeted, two-partner approach

What a practical preconception plan can include

1. 1
   Clarify goals and timing.

   Discuss desired family size, when you hope to start, age-related considerations, contraception, and any reason your timeline may need to change.

2. 2
   Review both reproductive histories.

   Include cycles and ovulation, pelvic symptoms, prior pregnancies or losses, infections, surgery, cancer treatment, testicular injury, erections and ejaculation, and family history.

3. 3
   Review every medication and supplement.

   Do not stop prescribed treatment independently. Flag testosterone or anabolic steroids, medications unsafe in pregnancy, and supplements with uncertain dose or purity.

4. 4
   Optimize health without perfectionism.

   Address smoking and vaping, cannabis, alcohol, sleep, movement, nutrition, dental care, chronic conditions, mental health, vaccination, and relevant occupational exposure.

5. 5
   Start folic acid.

   For most people who could become pregnant, Health Canada recommends a daily multivitamin containing 0.4 mg of folic acid, ideally beginning at least three months before pregnancy. Higher doses should be clinician-directed.⁶

6. 6
   Order tests that answer a clinical question.

   This may include targeted general health or hormonal tests, pelvic imaging, tubal assessment, or semen analysis. It should not automatically mean a large fertility panel.

7. 7
   Set a clear review point.

   Know when to return, what symptoms trigger earlier care, how results will be interpreted, and when a fertility, gynecology, or reproductive urology referral is appropriate.

Do not wait by default

When to seek a fertility evaluation

Seek care earlier at any age for absent or very irregular periods, suspected endometriosis or tubal disease, known uterine or ovarian disease, recurrent pregnancy loss, prior chemotherapy or pelvic radiation, a history that could affect the testes, known abnormal semen results, sexual dysfunction, or another condition known to affect fertility.^{7, 10}

Evaluation should begin with both partners when applicable. It should assess ovulation, reproductive anatomy or tubal patency when indicated, and semen. The purpose is not to run every available test. It is to locate the highest-value next decision.

Future projections and response

Low birth rates are likely to persist. Biological infertility is harder to forecast.

Statistics Canada's current scenarios all keep fertility below replacement through 2050.² International modelling also projects that most countries will remain below replacement by mid-century.²² These projections matter for schools, labour markets, healthcare, migration, and aging populations.

They still cannot tell us how many Canadians will meet a medical infertility definition in 2035 or 2050. That would require current, repeated data on time to pregnancy, pregnancy loss, reproductive diagnoses, male factors, treatment access, and who is trying to conceive. Treating a demographic projection as a biological forecast overstates the evidence.

A credible response therefore works at two levels:

• For individuals: earlier fertility education, inclusive preconception care, timely diagnosis of PCOS and endometriosis, parallel male assessment, STI prevention and treatment, tobacco cessation, evidence-based exposure reduction, and prompt referral when age or history warrants it.
• For health systems: better national surveillance, shorter diagnostic delays, fertility preservation counseling before gonadotoxic treatment, affordable and geographically equitable care, and reproductive health research that includes men.
• For society: childcare, housing, income security, parental leave, flexible work, and environmental and occupational protections. Biology and social conditions are not competing explanations. They interact.