From One Woman to Another: The Truth About Fertility and Aging
To continue the theme of how limited correct information about fertility and infertility is in at least parts of the general population, we asked a woman with considerable experience in the fertility industry to summarize for our female readers what she believes women should know about how age affects female fertility. And here is how she put it, simple and straightforward!
Introduction
The topic of age and fertility can feel overwhelming, caught between cultural pressure and biological realities that don’t always align with ones life’s timeline. Here’s the truth: yes, female fertility changes with age, but the story is more nuanced than the stark warnings you might have heard. Understanding what actually happens can help you make decisions that feel right for your life, not just your ovaries.
Women face a unique fertility challenge. Unlike men, who produce sperm throughout their lives, we are born with all the eggs we’ll ever have. This means our fertility story is intertwined with aging in ways that can’t be ignored but also shouldn’t cause panic.
The truth about the “35 deadline”
The idea that fertility sharply drops at 35 is a bit misleading. In reality, fertility begins to decline gradually in your late twenties and continues to decrease more noticeably through your thirties. It’s a steady shift, not an abrupt change, until roughly age 43, when the decline indeed accelerates. And while age is a factor, your biological age—your overall health and reproductive function—can be more relevant than your chronological age when it comes to fertility.
Your chance of naturally conceiving in a month with regular intercourse decreases from roughly 20-25% in your twenties to about 5% by age 40.1 Many women conceive naturally well into their late thirties and beyond. The key takeaway? It may simply take longer as you age, but that doesn’t mean it’s impossible.
Why regular periods don’t tell the whole story
Your body is remarkably good at maintaining regular cycles even as your egg supply dwindles. You can ovulate like clockwork while your fertility quietly declines behind the scenes.
Why does this happen?
As your ovaries age, they begin to work harder to maintain normal cycles, releasing higher levels of hormones to stimulate ovulation. Eventually, this system becomes less efficient, but long before that, your fertility potential may have already diminished. Regular periods are a good sign of hormonal balance, but they don’t always mean your fertility is still optimal.
The limits of modern fertility treatments
Here at the Center for Human Reproduction (CHR), we are a leading example of how far fertility treatments like in vitro fertilization (IVF) have come. But no matter how advanced the technology, it can’t reverse the natural aging process of eggs. IVF success rates still largely reflect a woman’s egg quality, which declines with age, among other factors.
At CHR, women over 42 (including some women into their early 50s) using their own eggs have live birth rates of around 5% per cycle start (our so-far oldest patient having a child with her own eggs was 48). Based on 2024 outcomes, the CHR’s approximate live birth rate for women with a median age of 45 (half were above and half below age 45) has from 2022 to 2024, however, increased from 8% to 12%, if their IVF cycle produced at least one day-3 cleavage age embryo for transfer.
These, still, relatively low rates obviously compare poorly to live birth rates of over 40% for women between the ages of 23 and 35 with normal age-specific functional ovarian reserve (women under age 23 have lower birth rates).2 This steep drop, however, isn’t a failure of IVF, but it’s a reflection of how egg quality impacts success, especially after age 40. Considering the very advanced age of the CHR’s patients and considering that most of the CHR’s patients have had repeated IVF failures elsewhere before even presenting to the CHR, the 2024 IVF cycle outcomes, indeed, have to be considered astonishingly good.
That’s why one of the most important things to understand is that egg quality—not your age—in principle drives most fertility outcomes. When younger donor eggs are used, success rates remain high, even for recipients in their mid-to-late fifties. This reinforces a key truth we always share with our patients. While your age matters, it’s really the age of your eggs that plays the most decisive role in treatment success, and some older women can have “younger-behaving” eggs. In comparison, some younger women may have “older-behaving eggs,” a condition called premature ovarian aging (POA), which affects ca. 10% of all women in the world.
What actually happens as you age
Your egg inventory
At birth, you have about 1-2 million eggs; by puberty, only 400,000 remain, and this number keeps falling by 35 at a faster rate. By 37, you’re down to 25,000 eggs, and the quality of remaining eggs also declines.3
Chromosome complications
As eggs age, they become more prone to chromosomal errors during cell division. Miscarriage risk rises, as does the likelihood of chromosomal conditions in offspring. The chance of chromosomal abnormalities in individual embryos jumps from about 2% in your twenties to over 35% at age 40.4 But don’t worry, nature is smart: most of these abnormal embryos do not implant and cause pregnancy and/or are very early miscarried. The risk of having a chromosomally abnormal ongoing pregnancy, therefore, even by age 40, is only ca. 1%.
Hormonal shifts
Aging ovaries struggle to produce adequate hormones. Your body compensates by releasing more FSH (follicle-stimulating hormone). These changes can affect everything from cycle timing to egg quality.5
Physical changes
The uterine lining may thin with age, potentially making implantation more difficult. Age also increases the likelihood of conditions like fibroids or endometriosis, both of which can interfere with conception.6
Assessing your individual fertility
Everyone’s fertility journey is different. Some women maintain robust fertility into their forties, while others experience earlier declines. Knowing where you stand is empowering.
Useful tests include:
AMH testing: Measures your functional ovarian reserve7
Day 3 FSH: Elevated levels may indicate declining ovarian function8
Antral follicle count: Ultrasound assessment of your egg supply9
Cycle tracking: Changes in pattern can signal hormonal shifts
Optimizing your reproductive health
While you can’t stop time, you can support your fertility in the following ways:
Weight matters: Both too little and too much body fat can disrupt ovulation and hormone balance.
Move your body: Regular, moderate exercise supports fertility, but intense training can actually suppress ovulation.
Fuel yourself well: Prioritize antioxidant-rich foods, healthy fats, and quality protein while limiting processed foods and excessive caffeine.
Stress less: Easier said than done, but chronic stress genuinely impacts hormone production and cycle regularity.
Sleep well: Poor sleep disrupts the hormones that regulate ovulation and fertility.
Avoid fertility disruptors: Limit exposure to environmental toxins, quit smoking, and moderate your alcohol consumption.
When to seek professional help
If you’re under 35 and have been trying for a year without success, or over 35 and trying for six months, it’s time to consider consulting a fertility specialist.10 Don’t wait if you have irregular cycles, a history of pelvic inflammatory disease, or known reproductive health issues.
Early evaluations empower you with information. Understanding your fertility status helps you make informed decisions about timing, treatment options, and family planning strategies.
A reassuring closing
Age affects female fertility—this is a biological fact, not scare tactics. Knowing this empowers you to make choices that align with your goals rather than being caught off guard. Some women will conceive easily in their forties, while others may face challenges in their twenties. Understanding your individual situation and having realistic expectations makes all the difference.
Your fertility depends on multiple factors: overall health, genetics, lifestyle choices, and yes, sometimes simple luck. Age is significant, but it’s one piece of a larger puzzle. Staying informed and proactive about your reproductive health helps you navigate this journey with confidence, whatever timeline feels right for your life.10
References: To facilitate the finding of additional detail, we here offer patients and other interested parties complete references
American College of Obstetricians and Gynecologists. Female age-related fertility decline. Committee Opinion No. 589. Obstet Gynecol. 2014;123:719-21.
Gleicher N. IVF Success Rates by Age, Over 40. Reproductive Health Blog. Center for Human Reproduction; May 4, 2020.
American Society for Reproductive Medicine. Testing and interpreting measures of ovarian reserve: a committee opinion. Fertil Steril. 2020;114:1151-7.
Hassold T, Hunt P. To err (meiotically) is human: the genesis of human aneuploidy. Nat Rev Genet. 2001;2:280-91.
National Institute of Child Health and Human Development. Age-related fertility decline. StatPearls. Updated February 2024.
Reproductive Medicine Associates. Ovarian vascular aging: a hidden driver of mid-age female fertility decline. NPJ Aging. 2025;11:1-12.
American Society for Reproductive Medicine. Ovarian reserve testing: a committee opinion. Fertil Steril. 2022;117:1201-8.
Broekmans FJ, Kwee J, Hendriks DJ, Mol BW, Lambalk CB. A systematic review of tests predicting ovarian reserve and IVF outcome. Hum Reprod Update. 2006;12:685-718
La Marca A, Volpe A. Anti-Müllerian hormone (AMH) in female reproduction: is measurement of circulating AMH a useful tool? Clin Endocrinol (Oxf). 2006;64:603-10.
American Society for Reproductive Medicine. Optimizing natural fertility: a committee opinion. Fertil Steril. 2022;117:53-63.