IVF Success Rates by Age: How to Read the Numbers Without Fooling Yourself

Why age matters so much

Age affects both how many eggs respond to stimulation and the quality of those eggs. HFEA explains that the chance of conceiving falls with age because egg quality and egg numbers both decline (HFEA). ASRM's ethics committee names age at the time eggs are collected, along with ovarian reserve, as a key predictor of success (ASRM Ethics Committee, 2023), and its practice committee states that age is a stronger predictor of reproductive success than ovarian reserve markers such as AMH (ASRM Practice Committee, 2020).

The age that counts for the eggs is the age of the person whose eggs are used, at the moment they were retrieved. Embryos created from eggs retrieved at 35 carry that egg age even if they are transferred at 42, although the age of the person carrying the pregnancy still matters for pregnancy health. HFEA notes that the risk of pregnancy complications also rises with age (HFEA).

What national data show

Two public sources show the age gradient clearly. They measure different things, which is the first lesson in reading any success rate.

The HFEA figures count births per embryo transferred, using fresh transfers with patients' own eggs and excluding cycles with genetic testing of embryos or donor eggs. The UK average on that measure was 25% (HFEA, 2025). The JAMA figures count live births per stimulation cycle, then add them up across repeated cycles (Smith et al., 2015).

Neither is a forecast for you, and both come from UK clinics. The value is in the direction and the size of the gap: in both sources, chances in the forties are a fraction of those in the thirties.

U.S. data and the CDC estimator

U.S. clinics report outcomes to CDC, which publishes own-egg results by age group and counts them cumulatively, including transfers within a year of each retrieval. Donor-egg results are reported per transfer instead (CDC, 2025).

CDC's IVF Success Estimator lets you enter an age between 20 and 50, with height, weight, diagnosis and prior pregnancies, and returns an estimated cumulative chance of a live birth over one to three retrievals (CDC, 2024). CDC cautions that the estimate may not reflect your actual chances. One practical use: run it at your age, then again five years older. The difference shows how much age alone moves the estimate for someone with your profile.

Own eggs versus donor eggs

Donor eggs change the age question. In the JAMA study, live-birth rates with donor eggs did not differ by the recipient's age (Smith et al., 2015). The egg-related chances follow the donor. The recipient's age still matters for pregnancy health.

This has a practical consequence. If a clinic quotes one success figure for "patients over 40" without saying whether it includes donor-egg cycles, it may make own-egg chances at that age look better than they are. Always ask which egg source a figure describes. If you are weighing that route, see what international patients should ask about donor-egg IVF in Medellín.

Five ways people fool themselves with age data

1. Using an all-ages average. A clinic-wide rate mixes 30-year-olds and 44-year-olds. Ask for your age band.
2. Ignoring the denominator. Per embryo transferred, per transfer, per retrieval and per cycle started give different numbers for the same patients. HFEA warns that figures abroad may be presented in flattering ways, such as including only women under 35 or counting pregnancies rather than births (HFEA, 2016). The denominator problem gets its own guide: how to compare IVF success rates.
3. Counting pregnancies, not births. A positive test is not a baby. Ask for live births.
4. Treating one cycle as the whole story. The per-cycle rate understates what several attempts can achieve, and a cumulative rate overstates what one attempt delivers. Both matter for planning, as covered in how many IVF cycles you might need.
5. Assuming a good test result cancels out age. A high AMH at 43 suggests more eggs, not younger eggs.

Age, embryo numbers and twins

Lower odds at older ages can create pressure to transfer more than one embryo to "make up" for age. According to HFEA, carrying twins or triplets is the single largest health risk fertility treatment creates for both mother and babies, which is why single-embryo transfer is the usual standard in UK clinics (HFEA, 2016). In the UK, the multiple birth rate after IVF fell to 3.4% in 2023, the lowest national average recorded (HFEA, 2025). Pregnancy risks also rise with the age of the person carrying the pregnancy, so a twin pregnancy at 43 is a different proposition from one at 30. Ask any clinic for its transfer policy by age and its own multiple birth rate before you discuss numbers of embryos.

What to ask a Medellín clinic

Colombian clinics are not part of the U.S. or UK national reporting systems, so you depend on each clinic's own figures. A fair request sounds like this: "For patients in my age band using their own eggs, how many live births per egg retrieval did you have last year, including frozen transfers from those retrievals? How many patients is that based on?"

A reply with a single rate, a pregnancy rate or no patient numbers has not answered the question. Small numbers can be honest too. A clinic that treated few patients in your age band should say so, because a percentage built on a handful of cycles can swing widely from one year to the next.

Turning age data into a decision

Age data are most useful when they feed a concrete decision. Three questions are worth answering for yourself before a consultation. How many retrievals am I prepared to do with my own eggs? At what point would I want to discuss donor eggs, and is that acceptable to me? If I am not ready to try for a pregnancy yet, does freezing eggs or embryos now change my options later? A clinic's numbers for your age band should help you answer each one, not replace your own priorities.

If you are over 40

Age data are hardest to hear in the forties, which is also where marketing tends to be most generous. The JAMA figures show that chances with your own eggs are lower but not zero at 40 to 42, and very low per cycle after 42 (Smith et al., 2015). ASRM's guidance on very low ovarian reserve adds that a likely limited response should guide counselling rather than automatically rule out treatment (ASRM, 2020). Our guide to IVF over 40 in Medellín covers how to judge a clinic's claims at that age.

Medical disclaimer: MedellinIVF.co is an independent educational and lead-navigation site, not a fertility clinic. Nothing on this page is diagnosis, treatment advice or a guarantee of outcome. Prices and policies change. Verify current information directly with the treating clinic and appropriate Colombian registries.