Does your fertility really fall off a cliff when you hit 35?

Has my fertility fallen off a cliff? Hearst Owned

There’s a scene from Sex And The City that’s been re-playing in my mind on a loop lately. It’s the episode where Carrie drags her friends to Atlantic City to celebrate Charlotte’s 36th birthday (Luck be an old lady, streaming now on a platform near you). The trip, perhaps an allegory for birthdays everywhere, turns out to be a let-down. But the scene I keep coming back to is Carrie gazing down at the roulette wheel as she couldn’t help but wonder: what happens after 36?

It’s a question I’ve been asking myself since I blew out the candles on my 35th birthday cake. Perhaps it’s because I’m halfway through a decade. Or maybe I lost too many of my fun years to Covid. But deep down I know why this most recent lap around the sun has bothered me so much. Of all the messages etched onto our amygdalas from the moment we get our first periods, one lingers longer - and louder - than most: at 35, your fertility falls off a cliff. And as I mark this milestone with an unoccupied womb, this threat hits different.

I suspect I’m not alone in swallowing some fertility anxiety with my Colin the Caterpillar this year. Be it by design or by circumstance, fewer women are becoming mothers. Data from the Office for National Statistics reveals that among women who turned 45 in 2021, almost one in five didn’t have children – a statistic that represents an increase of 13 per cent during a generation.

Meanwhile, those who are having children, are doing so later; the average age of first-time motherhood is now 31 - an increase of five years since the 1970s. That more women are trying to get pregnant in their 30s explains why egg freezing is the fastest growing fertility treatment, with the industry predicted to be worth £122m by 2027.

But the sizeable sums women are paying to kick the pram down the road are nothing compared to what this anxiety is costing women emotionally. ‘The fear of making the “right choice” within the “right window of time” is prevalent among the people I work with,’ says Dr Sophie Mort, a clinical psychologist with a largely millennial client base and the author of (Un)stuck: Five ways to break bad habits and get out of your own way.

‘While helpful in reminding people that there may be time constraints, metaphors like ‘the cliff’, ‘the clock is ticking’ and even ‘geriatric mother’ can lead to the kind of anxiety that grinds people’s decision making to a halt.’

This is precisely what’s happened to me. While I’m in a relationship with a man I’d be happy to merge my DNA with, my fertility anxiety isn’t motivating me to ‘try’. Instead, I feel incapable of making this – life-defining, irreversible – decision. And the more I dwell on ‘the cliff’, the more incapacitated I feel. So with my fertile future and mental health in mind, I need to know: has my fertility fallen off a cliff?


An understanding of when my fertility began its decline begins with an understanding of why – and a process called atresia; a concept you can file away with ‘getting a mortgage’ and ‘understanding your emotions’ in the folder marked ‘shit we weren’t taught about in school’. ‘Atresia is the normal physiological process by which a woman loses her eggs,’ says Dr Karin Hammaberg, Senior Research Fellow in the School of Public Health and Preventive Medicine at Monash University in Australia.

A baby girl is born with around a million eggs, she explains, but by the time she reaches puberty, there are around 300,000 left. Of these eggs, between 300 and 400 will mature and be released in ovulation during the reproductive years. But this isn’t just a numbers game; as you age, the quality of your eggs declines, too.

‘It’s estimated that about 20% of all human eggs are “aneuploid”, which means they have the wrong number of chromosomes and this proportion increases as women age,’ she adds. ‘When an aneuploid egg is fertilised by a sperm it gives rise to an aneuploid embryo – which in most cases stops developing or ends in an early miscarriage.’ It’s for this reason that the risk of miscarriage rises with age, with one study putting the risk at 10% for 25-29-year-olds, rising to 53% for women over 45.

Back in her native Sweden, Dr Hammaberg worked in the hospital where the first IVF baby in Scandinavia was born, before moving to Australia to study the experience of birth and mothering after fertility treatment. I came across her work via an article she published on the academic website The Conversation on whether the cliff is really a cliff. So…is it, I ask?

‘No, it’s not actually a cliff – and this is an important myth to dispel,’ she begins, before giving it to me straight. ‘But the chance of pregnancy every month does decrease as you get older. You can’t explain it away or wish it away. It’s just a fact.’ Generally speaking, she tells me, a slow decline happens between 30 and 35, after which the decline gets faster.

She points me a study published in 2016, which monitored the time it took a cohort of 960 women aged 30-44 to get pregnant; the chance of pregnancy after 12 months was 87% for women aged 30-31, 76% among those aged 36-37 and 54% among those aged 40-41. These numbers account for conception, rather than healthy pregnancies carried to term, so they tell us nothing about the miscarriage risk. But, crucially, when you plot these figures on a graph, they don’t resemble a cliff, but a gently declining hill.


Of course, statistics about ‘cohorts’ tell you nothing about your own ovaries. Dr Hammaberg is a walking, talking example of this; she fell pregnant unexpectedly at 45. And this fertility small print of ‘individuals may vary’ adds yet another layer of confusion to a conversation mired in the stuff. It’s into this context that ‘fertility MOTs’ – tests which deliver data on your own reproductive capabilities - enter the chat.

The umbrella term covers a range of tests, with the information gleaned varying from clinic to clinic, says Rachel Cutting, Director of Compliance & Information at the Human Fertilisation & Embryology Authority (HFEA), the organisation responsible for regulating the fertility industry.

‘Fertility MOTs can include testing for hormones such as follicle stimulating hormone (FSH) and anti-Müllerian hormone (AMH) and sometimes include an ultrasound scan.’ But while such tests can give you indication of your fertility, she adds, fertility MOTs don’t currently fall within the HFEA’s regulatory remit. It means that while anyone undergoing IVF can read ratings and reviews for the clinic they choose on the HFEA website (like a Trip Advisor for fertility treatment) the same system doesn’t exist for fertility MOTs.

But hospitals with a good rating on HFEA seem like a sensible place to start. And this is how I find myself with myself with my feet in a pair of stirrups as a consultant gynaecologist gives me a guided tour of my uterus.

I’m at the (5/5 rated) Lister Fertility Clinic at The Portland Hospital (part of HCA Healthcare UK) a stone’s throw from Regents Park, where I’m having the Fit For Fertility package – and it’s a package in demand. The clinical group saw a 162% rise in people seeking such consultations between 2021 and 2022, while the number of Fit for Fertility appointments between January and June this year has already surpassed last year’s total.

The female package (£450) includes a test measuring levels of anti-müllerian hormone (AMH – more of which later), an ultrasound scan and a 30-minute follow up consultation, condensed into an easy-to-digest report afterwards. But given my own fertility only tells one side of the story in my chances of conceiving, I bring my husband - and his sperm - along for good measure (£595 for a heterosexual couple, £730 for a lesbian couple – female tests are more extensive, making them more expensive).

A week later, we join Dr Linda Farahani, Consultant Gynaecologist and Specialist in Reproductive Medicine, on a Zoom call to discuss the results – me in a meeting room in my central London office, my husband in a classroom at the school where he teaches. I’m beginning to question the wisdom of arranging such a high stakes call for a working lunch hour when Dr Farahani begins to speak.

It's good news, overwhelmingly so. My uterus is arcuate, meaning it has a small dent at the top – a minor irregularity that doesn’t appear to have any clinical significance – while the result of my AMH test is 44.7. The score is out of 100, mine is at the higher end of normal for my age and correlates with the number of follicles (fluid-filled sacs that contain immature eggs) that Dr Farahani counted on my ovaries; 20 on the left, 22 on the right. Meanwhile, my husband’s sperm count was well within the normal range on every metric they tested.

These results aren’t just reassuring, they’re staggering. To explain why, we need to go back to October 2022. After a routine NHS ultrasound scan, I was told that my uterus was bicornate – a rare, congenital condition associated with a higher risk of miscarriage. Off the back of this – pretty gutting - news, we decided to get my husband’s sperm checked, too – via another NHS test.

Several weeks later, we put his phone on loudspeaker as the voice on the other end explained that his sample had low morphology. The metric refers to the size and shape of sperm, with morphology results reported as the percentage of sperm that appear normal when viewed under a microscope. This score, the man explained, would make it harder to conceive each month. ‘But I’m not really an expert,’ he added, in a baffling disclosure. ‘So you might want to get a second opinion.’ We did.

Dr Farahani waits patiently as we recount our story to her, before making herself very clear: I do not have a bicornate uterus; his sperm looks perfectly healthy. I don’t even know if I want children. But at I end the Zoom call, the emotions I’ve been suppressing for months collect in my tear ducts, dribble down my cheeks and land on the keyboard.


Here comes the disclaimer: I am in no way suggesting that spending hundreds of pounds on a fertility MOT package is the only solution to sating the anxiety which can come with being childless in your mid-30s. Nor do I believe the NHS fertility system is inherently flawed. But this is my reality: if I hadn’t sought out a second (private) opinion, I might still be sitting on an NHS waiting list for an IVF appointment in eight months’ time; an appointment I wasn’t sure I wanted, but arranged in a state of panic.

When I asked Dr Farahani how the NHS could have got both of our results so wrong, she reiterated that fertility isn’t a perfect science; sperm samples can change from month to month, while the person reviewing my ultrasound could have misinterpreted the extent of the indentation, in a way that altered my diagnosis.

Of course, if fertility isn’t a perfect science, how much can private tests really tell you? While the ultrasound and semen analysis revealed information that’s invaluable to our fertile future, research has cast doubt on the efficacy of AMH testing as a predictor of female fertility.

‘AMH is produced by the follicles and it helps both follicles and eggs to grow during the menstrual cycle,’ Dr Hammaberg explains. ‘Because the number of follicles in the ovaries drops with age, the level of AMH also falls.’ As such, the AMH level indicates the number of eggs in the ovaries, also known as your ovarian reserve.

But my score of 44.7 – a number that imprinted on my hippocampus faster than my phone number – tells me nothing about the quality of my eggs. And research suggests that a woman with a lower number would have the same chances of conceiving as me.

In a 2017 study exploring the correlation between AMH levels and the time it was took women aged 30 to 44 to conceive, the researchers found no association between a diminished ovarian reserve and infertility – findings which led them to caution women against using AMH testing to plan their reproductive future. The same conclusion was drawn from a 2019 study, which reiterated the inability of AMH tests to communicate anything about the quality of eggs. It means that, at strategies goes, this one is a long way from being a silver bullet.

So what can you do to get a read on the cliff? Dr Hammaberg is adamant that, currently, there is no reliable way to test female fertility; that all you can do if you want to test your ability to conceive is to ‘try’. Such advice is reasonable enough for those who have a partner they want to raise a child with. But it doesn’t serve single women, who are looking to learn more about their fertility with the goal of becoming pregnant via a sperm donor.

For these women, she adds, such a test can be helpful. ‘AMH testing is useful in the context of IVF treatment because it can tell you what dose of drugs you might need,’ she tells me, before adding for the avoidance of doubt. ‘But it can’t predict your chances of conceiving.’

This warning is echoed by Dr Farahani. ‘Your antral follicle count and AMH level do not predict your ability to conceive naturally,’ she explains. ‘The test is a snapshot in time and although we know that ovarian reserve declines with age, there is no way of predicting how quickly this will happen.’

But as far as my own fertile future is concerned, there is a silver lining. ‘If you were to proceed with fertility treatment at any point in the near future, I would expect that you would do very well with the values as they are.’ It’s a reassuring sentiment, albeit one I’m not ready to engage with. But I feel as confused as ever. Nobody, it seems – not even a doctor who's well-acquainted with my ovaries – can tell me what happens after 35.


Six months on from my fertility MOT, my ovaries are older, but none the wiser. That the dramatic language of fertility decline that I was raised on doesn’t tell the whole story of female fertility is an undeniable comfort.

As for the knowledge that some of the vital components required for the business of making babies are in working order, having spent the previous six months thinking they weren’t, the gratitude I feel over this particular piece of intel is humbling. But if the only way of testing my fertility is to ‘try’, it’s not a step I’m ready to take. And I won’t be ready until I know how I feel about a positive pregnancy test.

For now, I’m taking the same proactive approach to managing my fertility anxiety as I do to managing my mental health. I’ve re-started sessions with the therapist who I turned to during the lockdowns, and our fortnightly sessions have become a space to process my feelings around motherhood in a way that feels productive.

As for talk of ‘the cliff’, I’m learning to tune it out. ‘Try to find a balance between informing yourself of the facts and reading so much information that you feel more overwhelmed, confused and anxious,’ Dr Mort urges; advice perhaps I should have asked for before beginning work on this feature.

Next on my list is creating a support network of women who, like me, aren’t yet employed in the labour of mothering. ‘Hearing stories from people in the same boat as you will increase your ability to make an informed choice and ensure you feel connected to a community,’ she adds.

As one of the only women in my immediate friendship circle who isn’t currently pregnant or parenting, this part feels crucial. I’m making more of an effort with women in my wider social circle who, by chance or design, have also found themselves without children. And…it’s helping. Female fertility might be a game of roulette, but you don’t have to play it alone.

You Might Also Like