How Age Affects Fertility for Women and Men
Almost everyone knows that fertility declines with age. What surprises most people is where age actually does its work — and understanding that changes how you think about timing, testing, and treatment.
The short version: age doesn't mostly make it harder for a good embryo to become a baby. It mostly makes it harder to produce a good embryo in the first place. That distinction sounds subtle, but it shapes nearly every decision you might face, from when to get tested to whether treatments like IVF, egg freezing, or donor eggs make sense for you.
Below, we walk through what the most recent national data shows for women and for men, and what it means in practical terms. A quick note before we start: the figures here come from the Society for Assisted Reproductive Technology (SART) national summary, which combines results from member clinics across the country. National averages are a useful map of the landscape, but they are not a prediction for any one person — your own picture depends on your health history, diagnosis, and individual testing. Think of this as education, not a forecast.
How age affects female fertility
Women are born with all the eggs they will ever have, and both the number of eggs and the proportion that are chromosomally normal decline over time. That second part — chromosomal normalcy — is the piece that does the most damage to fertility with age, and it's the piece people understand least.
Here's why it matters. When an egg has the correct number of chromosomes, the embryo it creates is called euploid. Euploid embryos are the ones that can reliably implant and lead to a healthy pregnancy. As eggs age, a larger share produce aneuploid (chromosomally abnormal) embryos, which usually fail to implant or end in early miscarriage. So the older the eggs, the more embryos you typically have to create to find one that can succeed.
This is why it's more accurate to think of age-related decline as mostly a supply problem — how many good embryos you can produce — than a problem with whether a good embryo can succeed. The latest national IVF data makes the distinction plain. Measured per patient, the odds of a live birth from IVF using a woman's own eggs fall steeply with age: roughly half of women under 35 have a live birth, dropping to around 14% by 41–42 and to about 4% past 42. But measured per embryo transfer — that is, once a usable embryo is actually available to transfer — the decline is far gentler, still holding near 46% at ages 38–40.
The distance between those two ways of counting is the heart of the matter. What erodes with age isn't primarily an embryo's ability to implant; it's how often a cycle produces a transferable embryo in the first place. As age rises, a growing share of retrievals yield no usable embryo — climbing from well under 10% in the under-35 group toward nearly half past 42 — and more cycles never reach a transfer at all. By the early 40s, most retrievals using a woman's own eggs don't produce a transferable embryo. That upstream attrition, not implantation failure, is what accounts for most of the age-related decline. These figures come from the Society for Assisted Reproductive Technology's most recent national summary and describe national averages, not any individual's odds.
What genetic testing reveals about the age effect
This is where the euploid picture gets clarifying. When researchers look specifically at cycles where a chromosomally normal embryo was transferred — using preimplantation genetic testing for aneuploidy (PGT-A) to identify those embryos — much of the age gap narrows. Roughly half of euploid embryo transfers lead to a live birth, and that figure stays relatively strong across age groups. A woman in her early 40s transferring a euploid embryo has a meaningfully better chance than her per-patient odds alone would suggest.
The honest caveat: a modest age effect does persist even with euploid embryos. Large analyses show that success still edges down somewhat at older ages, so genetic testing doesn't erase age entirely — there appear to be smaller, additional age-related factors beyond chromosomes. But the dominant force, by a wide margin, is how many chromosomally normal embryos an egg supply can produce. Age is mostly a numbers problem at the front end, not a viability problem at the back end.
That reframing is genuinely useful. It's why two people the same age can have very different outcomes depending on egg quantity and quality, and it's why testing that measures your egg supply matters so much.
Understanding your own numbers
National averages describe a crowd, not you. The tests that describe you include AMH (anti-Müllerian hormone), which estimates your remaining egg supply, along with an antral follicle count and other markers your physician may order. Lower results don't mean pregnancy is off the table — but they do help explain how age is affecting your fertility specifically, which is far more actionable than any national average. If your results point toward diminished ovarian reserve (DOR), your care team can factor that into timing and treatment recommendations.
How age affects male fertility
Male fertility also declines with age, but it works differently — and understanding the difference matters, because male age is often left out of the conversation entirely.
Where female fertility drops fairly sharply in the late 30s and early 40s, male fertility declines gradually and continuously, with changes generally becoming more noticeable beginning in the 40s. According to the American Society for Reproductive Medicine (ASRM), advancing paternal age is associated with declines in semen volume, sperm motility, and sperm morphology, along with rising sperm DNA fragmentation and an accumulation of new (de novo) genetic mutations in sperm. It may also be linked to somewhat lower conception rates after IUI and IVF, and some studies associate it with higher risks of miscarriage and certain conditions in children — though those findings are less consistent.
A practical note on testing: standard semen analysis doesn't fully capture these age-related changes, and ASRM does not recommend routine sperm DNA fragmentation testing as part of a first fertility workup. It's most useful in specific situations — for example, in couples experiencing recurrent pregnancy loss (RPL) — where it may guide next steps. If male age is a factor for you, a conversation with your physician about whether additional testing is worthwhile is the right starting point, rather than assuming it's needed.
The takeaway for couples: age matters on both sides, and evaluating both partners early is simply good practice. Fertility is a shared equation.
What you can do about age and fertility
The most powerful lever in all of this is time — which means the most powerful thing you can do is get clear information sooner rather than later.
Get evaluated earlier than you think you need to. General guidance suggests seeing a fertility specialist after 12 months of trying if you're under 35, and after 6 months if you're 35 or older — but if you already know you want to understand your fertility, there's no reason to wait to trip that wire. Earlier evaluation simply gives you more options while they're still fully open.
Freezing eggs or embryos to work with younger biology
Because the age of the eggs is what matters most, freezing eggs (or embryos) when you're younger is one of the few ways to genuinely work with time rather than against it. Eggs frozen at 32 remain "32-year-old eggs" whenever you use them — you're essentially preserving today's biology for a future decision.
Egg freezing isn't only for people who are certain they want to delay parenthood. It's also worth considering if you're not ready to try now but want to protect the option, if you're facing a medical treatment that could affect fertility, or if testing suggests your egg supply is declining faster than average. It won't guarantee a future pregnancy, and outcomes still depend on how many eggs are stored and the age at which they're frozen — but for the right person, it meaningfully widens the window. We walk through exactly how it works, the timeline, and what to expect in our guide to egg freezing in Tennessee.
When it makes sense to start thinking about donor eggs
For some people, the most effective path to a healthy pregnancy is using donor eggs — and thinking about that option earlier rather than as a last resort can spare a lot of heartache and time.
Here's the logic, and it flows directly from everything above. If age's main effect is on egg quantity and the proportion of embryos that are chromosomally normal, then using eggs from a younger donor addresses that specific bottleneck directly. Donor egg success depends mainly on the age of the eggs, not the age of the person carrying the pregnancy — the uterus generally remains receptive to pregnancy well beyond the age at which a person's own eggs decline. In the latest national data, live birth rates with donor eggs and embryos remain strong regardless of the recipient's age, which reflects that younger egg biology at work.
It may be worth starting the conversation about donor eggs if any of the following apply:
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Repeated IVF cycles have produced few or no chromosomally normal embryos
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Testing shows significantly diminished ovarian reserve at a younger age
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You're in your mid-40s or beyond and using your own eggs
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A medical history makes using your own eggs unlikely to succeed
None of this means your own eggs can't work — many people succeed with their own eggs at older ages — but knowing donor eggs exist as a high-success option, and understanding when they enter the picture, lets you make decisions on your timeline instead of under pressure.
This is often an emotional decision, and there's no single right answer or right time. The goal is simply to have the information early enough that it's genuinely a choice.
Frequently asked questions
At what age does female fertility start to decline? Fertility begins a gradual decline in the early 30s, becomes more pronounced after about 35, and declines more steeply in the early 40s. The main driver is a falling number of eggs and a rising proportion of chromosomally abnormal embryos.
Does IVF overcome age-related infertility? IVF can help, but it doesn't reverse the underlying biology. Because older eggs produce fewer chromosomally normal embryos, IVF success rates using your own eggs also decline with age. IVF's advantage is that it lets your care team retrieve multiple eggs and, with genetic testing, identify the embryos most likely to succeed.
Does male age affect fertility? Yes. Male fertility declines gradually with age, generally becoming more noticeable in the 40s, with changes in sperm quality, rising DNA fragmentation, and a slow accumulation of genetic mutations. The decline is more gradual than in women but still relevant, especially for couples where both partners are older.
Is it too late to freeze my eggs at 38? It's not about a hard cutoff — it's about the trade-off. Eggs frozen at 38 are younger than eggs frozen at 42, so earlier is better, but freezing can still be worthwhile at 38 depending on your egg supply and goals. Testing and a consultation will tell you what to realistically expect.
When should we consider donor eggs? It's worth discussing donor eggs if repeated cycles yield few or no normal embryos, if testing shows significantly reduced egg supply, or if you're using your own eggs in your mid-40s or beyond. Donor egg success depends mainly on the egg's age, so it remains a high-success option for many people whose own eggs are no longer the best path.
The Bottom Line
Age affects fertility mostly by shrinking the supply of chromosomally normal eggs and embryos — not by closing the door on pregnancy. That's actually good news, because it means the most valuable thing you can do is get clear, personal information early, while your options are widest. Whether that leads to trying now, freezing eggs for later, pursuing IVF with genetic testing, or exploring donor eggs, the right next step is understanding where you stand.
The team at Tennessee Fertility Institute can help you do exactly that, with testing and guidance tailored to your history and your goals. Request a consultation today to talk through your options with a specialist.