Something interesting is happening with fertility around the world. Birth rates are falling. Infertility affects millions of people. Demand for fertility care is increasing. So why is infertility increasing—or at least appearing more common—among younger adults?
We are learning more about how metabolism, hormones, nutrition, environmental exposures and overall health may influence our ability to create and sustain new life.
But before we jump to the conclusion that everyone’s reproductive system is simply breaking down, there is an important distinction to make.
Fertility rates and biological fertility are not the same thing.
The United Nations reports that the global total fertility rate has fallen from 3.31 births per woman in 1990 to approximately 2.25 today, with more than half of countries and territories now below the replacement level of 2.1. (United Nations)
But a population’s fertility rate reflects much more than reproductive biology. Economic security, housing costs, relationships, childcare, cultural expectations, contraception, personal choice and the age at which people decide to have children all influence how many children are actually born. In fact, UNFPA’s 2025 State of World Population report found that many people who want children are having fewer than they would like because of financial pressure, housing, job insecurity, lack of a suitable partner and concerns about the future. (United Nations Population Fund)
So declining birth rates don’t automatically mean that human fertility is declining. But clinical infertility is a very real health issue.
The World Health Organization estimates that approximately one in six people of reproductive age experience infertility during their lifetime. Infertility can involve male factors, female factors, both partners, or “remain unexplained.” (World Health Organization) This is where the conversation gets much more interesting.
At MyHealth1st, we don’t view fertility as simply the ability to get pregnant. We see it as one expression of vitality and an important indicator of whether the body possesses the conditions necessary to create and sustain new life.
That means that when fertility changes, we shouldn’t look only at the reproductive organs. We need to look at the whole person.
Dr. Young often describes human life in three broad stages:
These stages aren’t simply about reproductive organs turning on and eventually turning off. They reflect something much bigger: the body’s overall capacity to grow, adapt, reproduce, repair and thrive.
That is why fertility can be such an interesting health marker. The same biological systems that support reproductive function are connected to metabolism, hormone production, nutrition, cardiovascular health, sleep, stress regulation and immune function. Pretty cool, huh?
When those systems become disrupted, fertility may be affected too. And this brings us to an important correction to the way fertility is often discussed.
Fertility is not just a women’s health issue.
When a couple struggles to conceive, much of the attention traditionally lands on the woman. Naturally, there is good reason to evaluate female reproductive health. Ovulation, ovarian reserve, egg quality, endometriosis, PCOS, uterine health and hormones can all play important roles.
BUT, men are half of the reproductive equation. Male factors contribute to infertility in a substantial proportion of couples, and male infertility can involve low sperm numbers, impaired movement, abnormal morphology and other reproductive problems. (World Health Organization)
And, sperm are considerably more interesting than the tiny swimming tadpoles they sometimes get reduced to in biology textbooks.
Sperm carry more than just DNA. They also carry epigenetic information, including DNA methylation patterns, histone modifications and small regulatory RNAs that may influence early embryo development and potentially aspects of offspring health. Research is increasingly exploring how paternal nutrition, obesity, smoking, stress and environmental exposures can alter the sperm epigenome. (PubMed)
This doesn’t mean a man’s lifestyle determines his child’s future. Human biology is far too complicated for that kind of neat cause-and-effect story. But it does mean that the father’s health before conception may matter in ways we once underestimated.
Paternal metabolic health has become a particularly interesting area of research. Obesity in men is associated with hormonal changes, oxidative stress, impaired sperm production, altered sperm DNA and changes in sperm epigenetics. These factors may affect fertility and, potentially, embryo and offspring health. (ASRM) A major review of paternal obesity and offspring health described possible effects involving sperm DNA methylation, chromatin changes, small RNA molecules and DNA damage. (PubMed)
There is even emerging research suggesting that paternal health may influence aspects of the pregnancy itself. For example, a prospective cohort study involving 7,683 pregnancies found associations between paternal obesity and pregnancy complications including preeclampsia, cesarean delivery, abnormal fetal growth and postpartum hemorrhage. (PubMed)
This research is fascinating, but it deserves a bit of scientific humility. An association does not prove that a father’s weight directly causes a mother’s pregnancy complication. Couples typically share environments, behaviors, socioeconomic factors and other variables that can influence both partners.
Still, the findings reinforce an important concept: Pregnancy health doesn’t begin and end with Mom. Both parents contribute biological information and health influences before conception.
One of the most discussed findings in male reproductive health is the apparent decline in sperm counts. A major meta-analysis estimated that sperm concentration declined by 51.6% and total sperm count by 62.3% among unselected men between 1973 and 2018. The researchers also reported that the rate of decline appeared to accelerate after 2000. (Frontiers)
That is a striking finding. But it is important to phrase it accurately. It is an estimate from a large meta-analysis, not proof that sperm counts have declined identically in every population or that one particular environmental factor caused the change. Researchers continue to debate methodology, contributing factors and mechanisms. Still, the broader question is difficult to ignore….
Why are we seeing concerns about sperm quality at the same time we are seeing rising rates of obesity, insulin resistance, metabolic dysfunction, chronic disease and exposure to thousands of industrial chemicals? Perhaps these aren’t entirely separate conversations.
The relationship between metabolic health and reproduction is one of the clearest examples of why fertility shouldn’t be viewed in isolation. The American Society for Reproductive Medicine recognizes that obesity can impair reproductive function in both men and women. In men, obesity has been associated with hormonal changes, impaired semen quality, oxidative stress, sperm DNA damage and lower testosterone. (ASRM)
Insulin resistance, excess visceral fat and chronic inflammation can disrupt hormonal signaling. And hormones don’t exist in a vacuum either. Testosterone, insulin, cortisol, thyroid hormones, body composition, sleep and energy metabolism are all part of an interconnected system.
This is why fertility can sometimes function as a kind of biological “check engine” light. The signal doesn’t tell you exactly which component needs repair. It tells you that something deserves attention. Fertility can do something similar.
Testosterone is another area where the fertility conversation needs more nuance. Men with symptoms of low testosterone may experience fatigue, reduced libido, changes in body composition, decreased muscle mass and other symptoms that can meaningfully affect quality of life. But when a man wants children now or in the future, simply prescribing testosterone isn’t always the appropriate answer.
In fact, exogenous testosterone can suppress sperm production, sometimes dramatically. Testosterone therapy provides negative feedback to the brain and pituitary, reducing the hormonal signals needed to stimulate the testes to produce sperm. In some men, sperm production can decrease substantially or stop altogether. (ASRM)
That doesn’t mean men with low testosterone have to choose between feeling better and preserving fertility. It means we need to ask a better question:
Sleep disruption, excess visceral fat, insulin resistance, inadequate nutrition, chronic stress, certain medications and other medical conditions can all contribute to low testosterone.
Depending on the underlying cause, a fertility-conscious approach may involve improving sleep, nutrition and metabolic health, correcting identified nutrient deficiencies, addressing excess body fat or considering medications that stimulate the body’s own testosterone production.
Medications such as clomiphene or enclomiphene may also be considered in appropriate patients because they work through the body’s hormonal signaling pathways rather than simply replacing testosterone from the outside. Clomiphene and similar medications are used off-label in men in certain circumstances, and the appropriate treatment depends on symptoms, laboratory findings, underlying physiology and reproductive goals. (ASRM)
This is why MyHealth1st measures first and treats individually. Hormone optimization should never be a one-size-fits-all protocol.
Metabolic health isn’t the only piece of the fertility puzzle. We also live in an environment filled with substances that can interact with human biology in ways we are still learning to understand.
Phthalates, BPA, PFAS and other endocrine-disrupting chemicals are being studied for their potential effects on reproductive hormones and sperm health. A 2026 systematic review examining phthalates and male fertility found evidence of associations between phthalate exposure and altered semen parameters, including sperm concentration, motility and overall semen quality, while also emphasizing variability among studies and the need for additional research. (PubMed)
Research has also investigated associations between BPA exposure and semen parameters. The point isn’t to convince you that every plastic container in your kitchen is secretly plotting against your future grandchildren. It is to recognize that cumulative environmental exposure is worth considering, particularly when we have many practical opportunities to reduce unnecessary exposure.
Choosing glass or stainless steel when we can, avoiding unnecessary heating of food in plastic, reducing heavily fragranced products and paying attention to household and personal-care products are reasonable ways to reduce exposure.
The fertility conversation can get very complicated very quickly, but some of the basics remain surprisingly unglamorous.
Nutrition matters. Sleep matters. Movement matters. Stress matters. Body composition matters. Alcohol, nicotine, cannabis and other drug exposure matter. Ultra-processed food intake matters. Nutrient deficiencies matter. And no, spending most of the day sitting in a chair followed by 30 minutes of frantic exercise does not necessarily erase the previous 10 hours of being a human paperweight at our desk!
Cannabis deserves particular consideration. Research has associated cannabis exposure with changes in several semen parameters, although findings are not entirely consistent and the relationship with testosterone is less clear. (World Health Organization) The same principle applies to other substances, medications and environmental exposures: context matters, individual risk varies, and the goal isn’t fear. The goal is awareness.
Perhaps the most important shift is moving from fertility treatment toward fertility preparation.
Assisted reproductive technologies such as IVF and IUI are incredibly valuable, and fertility specialists play an essential role in helping people build families. But reproductive medicine shouldn’t be the only place where fertility health begins. There is an opportunity to work upstream.
Instead of waiting until conception becomes difficult, couples can use the years before pregnancy to improve metabolic health, optimize nutrition, build muscle, improve sleep, address hormonal concerns, reduce chronic stress and identify potentially modifiable environmental exposures.
And this applies to both partners. A woman’s health matters before pregnancy. A man’s health matters before conception. And the health of the couple matters long before either person sees a positive pregnancy test.
At MyHealth1st, we believe fertility is an expression of overall vitality and whole-body health. We don’t want to look only at whether conception occurs. We want to understand whether the body has the biological resources and resilience needed to create and sustain new life.
That means looking at the bigger picture, such as metabolism, hormones, nutrition, body composition, sleep, stress, lifestyle, environmental exposures, and… the health of both prospective parents.
Our approach may include comprehensive biomarker testing, fertility-conscious hormone optimization when appropriate, nutrition and body composition guidance, sleep and stress management, and strategies to reduce unnecessary toxic and environmental exposures.
The goal isn’t to promise that a perfect diet or a supplement regimen will guarantee pregnancy. Fertility is far too complex for guarantees. The goal is to create a healthier biological foundation before fertility becomes a crisis.
At the end of the day, healthy babies start with healthy parents. And perhaps that’s the bigger conversation we should be having. Not simply, “How do we get pregnant?”
But: “How healthy are we before we bring another human being into the world?”
If you’re thinking about starting a family, concerned about fertility, experiencing symptoms of hormonal or metabolic dysfunction, or simply want to optimize your health before conception, we can help you take a proactive approach.
Contact MyHealth1st to schedule a consultation today.
Your reproductive health doesn’t exist in isolation. It is part of the larger story of your health, your vitality and, potentially, the health of the next generation.
Erin is a National Board Certified and Functional Medicine Certified Health Coach with a passion for fitness, holistic wellness, and ethical food production.
