IVF after 35 and after 40

What actually changes with age

The main age-related change in IVF is in the eggs themselves, not necessarily in the ability of the womb to carry a pregnancy. As age increases, the number of eggs retrieved at a collection tends to fall on average, and a higher proportion of those eggs and the embryos formed from them tend to have chromosome abnormalities.

This is why age is described as affecting egg quality and quantity together, rather than one or the other on its own.

Why this matters at each stage of the process

• Ovarian stimulation may produce fewer eggs, and clinics sometimes adjust medication doses based on ovarian reserve tests like AMH and antral follicle count.
• Fertilisation and embryo development rates can be affected if egg quality is reduced.
• A higher proportion of embryos may be chromosomally abnormal, which affects implantation chances and miscarriage risk.
• Cumulative live birth rate across a full round of treatment, including any frozen embryos, is generally a more informative figure than a single transfer's result.

Under 35

This age group generally has more eggs retrieved on average and a lower proportion of chromosomally abnormal embryos than older age groups, though there is a wide range between individuals.

35 to 40

Outcomes in this range vary more between individuals than in other age bands, and ovarian reserve testing becomes more useful for understanding an individual's own situation rather than relying on age alone.

Over 40

HFEA published data shows outcomes using a person's own eggs are generally lower in this age group than in younger groups, on average. Some clinics discuss donor eggs at this stage, since outcomes using donor eggs depend mainly on the donor's age rather than the recipient's age.

HFEA's published national data breaks outcomes down by age band using consistent definitions, which is a better source for understanding general patterns than any single article, including this one. No average figure can tell you what will happen in your own treatment.

What NHS and private funding rules say about age

NICE guidance and local NHS commissioning policies often set age limits for NHS funded IVF, and these limits vary by area. Check with your GP or local integrated care board what applies to you, since these rules are set locally rather than uniformly across the UK.

Questions to ask your own clinic

• What do my own ovarian reserve results, such as AMH and antral follicle count, suggest about likely egg numbers?
• How does my clinic's data for people my age compare with the national HFEA figures?
• Would additional testing, such as PGT-A, be relevant given my age, and what would it add?
• Is donor egg treatment something worth discussing at this stage, and what would that involve?

What age does not determine on its own

Age is one factor among several, including the underlying cause of infertility, sperm quality, and the specific clinic and protocol used. Two people of the same age can have very different individual results, which is why your own test results matter more than an age band alone.