Medically reviewed content. Last updated: April 2026.
Medically reviewed content. Last updated: April 2026.
You have probably heard that fertility "falls off a cliff" at 35. The reality is more nuanced than the headlines suggest. While age does affect fertility, the decline is gradual, not sudden, and many people conceive naturally well into their late 30s and beyond. This guide separates fact from fear and explains what the evidence actually shows.
Yes, fertility does decline over time, and this is a biological reality. The key facts are:
However, the decline is gradual. There is no biological switch that flips at 35. That number comes from medical guidelines that use it as a threshold for offering additional screening and earlier fertility referrals, not because something dramatic changes on your 35th birthday.
Monthly conception rates (the chance of getting pregnant in any given cycle) decrease with age, but they remain meaningful well into the late 30s.
Cumulative rates tell a more encouraging story. According to a study published in Obstetrics and Gynecology, among women aged 35 to 39 having regular unprotected sex:
For those aged 38 to 39 specifically, a Danish study found that 78% conceived within 12 months of trying.
These are population averages, and individual experiences vary widely depending on overall health, lifestyle, partner fertility, and other factors.
The widely cited statistics about fertility decline after 35 can be traced partly to a 2004 study by David Dunson, published in Obstetrics and Gynecology. However, much of the public perception is based on even older data. Some of the most frequently quoted figures come from French birth records from the 1700s and 1800s, before modern nutrition, healthcare, and contraception.
More recent research using contemporary populations paints a less alarming picture. A landmark 2013 study by Jean Twenge, drawing on data from Dunson and others, found that the difference in fertility between 28-year-olds and 37-year-olds was relatively modest: in one dataset, 86% of 37-year-olds conceived within a year compared to 84% of 27-year-olds.
The important caveat is that these statistics apply to people trying to conceive naturally. IVF success rates, which are often quoted in fertility discussions, decline more steeply with age because they reflect a population that has already been unable to conceive naturally.
This is the biggest factor. As eggs age, they are more likely to have chromosomal abnormalities. This increases the risk of failed fertilisation, failed implantation, and chromosomal conditions such as Down syndrome. The change is gradual but accelerates after around 37 to 38.
The number of eggs available decreases over time. Tests such as AMH (anti-Mullerian hormone) and antral follicle count can give an indication of your remaining egg supply, but they do not predict your ability to conceive naturally. A low AMH means fewer eggs, not poor quality eggs.
Cycles may become slightly shorter or more irregular in the late 30s and early 40s as hormonal patterns shift in the years approaching menopause. Ovulation may become less predictable.
Certain pregnancy complications are more common with increasing age, including gestational diabetes, pre-eclampsia, placenta praevia, and caesarean delivery. However, with good antenatal care, most people over 35 have healthy pregnancies and babies.
On average, it takes longer to conceive at 35 than at 25. This does not mean it will not happen, just that patience may be needed. The key message from NICE is that if you are 36 or older and have not conceived after six months of regular unprotected sex, you should see your GP for initial investigations rather than waiting the full 12 months recommended for younger people.
While you cannot change your age, there are evidence-based steps that support fertility at any age.
Take folic acid (400mcg daily) and vitamin D (10mcg daily) from the time you start trying. If you are over 35, some fertility specialists also suggest CoQ10, though this is not part of standard NHS guidance.
Understanding your ovulation pattern becomes more important as you get older, particularly if your cycles are becoming less regular. Ovulation predictor kits, basal body temperature tracking, and cervical mucus awareness can help you identify your fertile window.
NICE recommends that people aged 36 or older see their GP after six months of trying. There is no benefit in waiting longer, and early investigation means earlier access to treatment if needed. Your GP can arrange blood tests and a semen analysis for your partner as a starting point.
If you know you want children but are not ready yet, it is worth having an honest conversation with your GP about your options. Egg freezing is becoming more accessible, though it is not guaranteed and is expensive (typically £3,000 to £5,000 per cycle plus annual storage fees). Understanding your individual situation, including your AMH levels and overall health, can help you make informed decisions about timing.
If you need help conceiving, the main options include:
Access to NHS-funded treatment varies by region, so check with your local Integrated Care Board for specific eligibility criteria in your area.
The average age of first-time parents in the UK is now 31 for women and 33.7 for men. In London, the average is even higher at 32.5. Having children later is increasingly common, and the healthcare system is well equipped to support it.
Being over 35 does not mean you have missed your chance. It means being informed, proactive, and willing to seek help earlier if things are not happening as quickly as you would like. For most people, the story ends with a healthy pregnancy and a healthy baby.
Yes, fertility does decline over time, and this is a biological reality. The key facts are:
Monthly conception rates (the chance of getting pregnant in any given cycle) decrease with age, but they remain meaningful well into the late 30s.
The widely cited statistics about fertility decline after 35 can be traced partly to a 2004 study by David Dunson, published in Obstetrics and Gynecology. However, much of the public perception is based on even older data. Some of the most frequently quoted figures come from French birth records from the 1700s and 1800s, before modern nutrition, healthcare, and contraception.
While you cannot change your age, there are evidence-based steps that support fertility at any age.
If you need help conceiving, the main options include:
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