IVF Success Rate by Age: What the Published Data Actually Shows

The first problem: “success rate” does not mean one thing

Before comparing any two numbers, you have to know what the bottom half of the fraction is. Clinics quote at least four different measures, and they are not interchangeable.

What is being measured	Why it matters
Per cycle started	Counts everyone who began stimulation, including cycles cancelled for poor response. The most honest denominator, and the lowest number.
Per egg retrieval	Excludes cancelled cycles. Higher than per cycle started.
Per embryo transfer	Counts only women who reached transfer. Excludes those with no usable embryo — which is precisely the group with the poorest prognosis. This inflates the figure substantially.
Cumulative, per retrieval	Counts the fresh transfer plus every frozen transfer from the same egg collection. Closest to the question a couple is actually asking: “if I do one IVF cycle, what are my chances of a baby?”

A clinic quoting “70% success” per embryo transfer and a clinic quoting “45% success” per cycle started may be delivering identical results. When a figure is given to you without its denominator, it is not information.

The second thing to check is the outcome. Pregnancy rate and live birth rate are different numbers, and the gap between them is not small — a proportion of pregnancies miscarry. A live baby is the outcome that matters, so that is the figure worth asking for.

The published figures, by age

India does not currently publish national outcome data. The National ART and Surrogacy Registry established under the ART (Regulation) Act, 2021 collects cycle data, but age-banded national success rates are not in the public domain. That means any “national average for India” you see quoted on a clinic website is not sourced from an audited registry.

The two large registries that do publish audited, age-banded data are SART in the United States and the HFEA in the United Kingdom. The figures below are the most recent published.

Age at egg collection	Live births per egg retrieval (cumulative, SART 2023)
Under 35	53.2%
35–37	39.9%
38–40	26.2%
41–42	13.2%
Over 42	4.1%

These are cumulative figures — they include the fresh transfer and all frozen transfers from that egg collection, across 425,869 cycles reported by member clinics. The UK data, measured differently as birth rate per embryo transferred, shows the same shape: around 35% for women aged 18–34 in 2022, falling to 10% at 40–42 and 5% at 43–44.

Why your own number is not the registry number

The registry average is the average of thousands of very different couples. Yours depends on a small number of factors, and most of them are measurable before you start.

Age of the eggs

This is the single strongest predictor, and it works through embryo genetics. As eggs age, the proportion of embryos with the wrong number of chromosomes rises. Those embryos either fail to implant or miscarry. This is why a woman of 42 with a normal AMH and a normal-looking ovary still has a low live birth rate: the problem is inside the egg, not the ovary’s ability to produce it.

If donor eggs from a young donor are used, the success rate tracks the donor’s age, not the recipient’s. That single fact is the clearest evidence that egg age, not uterine age, is the limiting factor for most women.

Ovarian reserve

AMH and antral follicle count predict how many eggs you are likely to collect, which affects how many embryos you get and therefore how many attempts one retrieval buys you. They are poor predictors of egg quality. A low AMH at 31 is a very different situation from a low AMH at 41, and the two should not be counselled the same way.

The sperm

A routine semen analysis measures count, motility and morphology. It does not measure DNA fragmentation, which is a recognised contributor to poor embryo development and to implantation failure. Where there have been failed cycles with good-looking eggs, this is worth testing rather than assuming.

The uterus

Submucous fibroids, endometrial polyps, intrauterine adhesions, a thin endometrium and untreated hydrosalpinx all reduce implantation. Most are correctable, and most are found on a saline sonogram or diagnostic hysteroscopy before the cycle rather than after two failed transfers.

The laboratory

Between two clinics with similar patients, the embryology laboratory is the largest remaining variable — air quality, incubator stability, culture media, and the experience of the embryologist handling your gametes. This is difficult for a patient to assess from outside, which is why the questions below matter.

One cycle or three? The cumulative picture

Most couples plan around a single cycle, but IVF outcomes are better understood cumulatively. A woman under 35 who does not conceive on her first transfer still has good odds across the frozen embryos from the same retrieval, and better odds again across a second retrieval. Counselling that presents only the first-attempt figure understates what a full course of treatment can achieve — and counselling that presents only the cumulative figure understates what the first cycle will cost.

Both numbers should be given to you, in writing, before you start.

What to ask before you choose a clinic

• Is the figure you are quoting a live birth rate, or a pregnancy rate?
• Is it per cycle started, per retrieval, or per transfer?
• What is it for my age band specifically, not overall?
• Does it include cycles that were cancelled?
• Is the clinic registered under the ART (Regulation) Act, 2021, and at what level?
• Will I get a written, itemised cost estimate before starting?

A clinic that answers all six plainly is telling you something useful about how it practises. A clinic that offers one large percentage and no denominator is telling you something too.

When IVF is genuinely the right next step

IVF is a treatment for specific problems, not a default. It is clearly indicated for blocked or absent fallopian tubes, severe male factor infertility, failed ovulation induction or repeated IUI failure, significant endometriosis, and where age makes waiting costly. It is often not the right first step for anovulation that has never been treated, for an untreated thyroid or prolactin abnormality, or for a couple who have been trying for eight months with normal investigations.

The question worth asking at the first consultation is not “what is your success rate” but “what exactly is wrong, and is IVF the treatment for it”.

Sources

1. Society for Assisted Reproductive Technology. National Summary Report, 2023 preliminary data: live births per intended egg retrieval by patient age. sartcorsonline.com
2. Human Fertilisation and Embryology Authority. Fertility treatment: key facts and statistics, 2022 data. hfea.gov.uk
3. The Assisted Reproductive Technology (Regulation) Act, 2021, Government of India — provisions on registration of ART clinics and reporting to the National Registry.