Understand fertility clinic success rates
On this page:
- What are success rates?
- How do we present clinics’ success rates?
- League tables and what to keep in mind when looking at success rates
- Why do success rates differ between clinics?
- I am looking at the websites of a number of clinics to decide where to go for treatment and am trying to make sense of success or pregnancy rates. What should I do?
- How can I see success rates relevant to me?
- Data on multiple births (twins and triplets)
- Clinical pregnancy rates
- Intra uterine insemination (IUI) with partner sperm data
- How old are the success rates published on this site?
- How do we get the figures?
- How do we compare clinics’ success rates to the national average?
- Why do we present the predicted chance of a live birth as a range?
What are success rates?
The HFEA presents success rates for every licensed clinic.
Success rates show the number of treatments carried out by the clinic in a particular year and the number of pregnancies or live births that were born as a result.
The success rates we publish should only be used as a general guide to a clinic’s performance. The majority of clinics’ success rates are around the national average.
There are other factors important when choosing a clinic, for example its location, the treatments and services it offers and the staff available. You may also want to look at the HFEA inspection reports for a clinic.
You can find this information along with clinic success rates in the individual clinic listings through our ‘Choose a fertility clinic’ search.
How do we present clinics’ success rates?
We show a clinic’s success rates in three different ways:
- Whether the clinic’s success rate is above, below or consistent with the national average success rate across all clinics
- The actual number of treatment cycles a clinic carried out and how many of those cycles resulted in a live birth
- The predicted chance of an average woman having a live birth if she was treated at this clinic
There are different ways to measure the success of an IVF or ICSI treatment. For example you can look at how likely a treatment cycle will lead to a live birth or how likely each embryo that is transferred during treatment will lead to a live birth. We show both live birth per cycle started and live births per embryo transferred.
For more details see:
League tables and what to keep in mind when looking at success rates
It is not meaningful to directly compare clinics’ success rates or create ‘league tables’ of clinics’ performance because:
- Clinics treat patients with different diagnoses and this will affect the average success rates we show for clinics
- Most clinics carry out too few cycles each year to reliably predict a patient's future chance of success
- The success rates relate to a period of treatment from about two years ago and may not be a good indication of success rates at the particular clinic today
Why do success rates differ between clinics?
Success rates can be affected by:
- the type of patients a clinic treats eg, their age, diagnosis and length of infertility
- the type of treatment a clinic carries out
- a clinic’s treatment practices
A clinic that treats proportionately more patients with complicated diagnoses may have a lower average success rate than clinics that treat more patients with common fertility issues.
I am looking at the websites of a number of clinics to decide where to go for treatment and am trying to make sense of success or pregnancy rates. What should I do?
Making accurate comparisons between clinics is always difficult as the success rates of one clinic may vary from another due to a range of factors, most notably the particular medical history of the patients treated.
The best way of making decisions about where to be treated is to visit our Choose a Fertility Clinic service which provides impartial information about all licensed fertility clinics in the UK. The information we publish there has been verified. As well as data about success rates, Choose a Fertility Clinic also explains what the statistics mean and degree of confidence with which comparisons can be made.
- Overall, it is important to not overly rely solely on published success rates because
They do not reflect the possible difference in the patients who go to different clinics (case mix)
- They do not reflect the fact that different clinics choose to treat some patients, but not others (this is called selection criteria)
- And they do not reflect your individual circumstances and all the possible factors that might affect your treatment prospects
You should therefore make up your own mind about what clinics claim; and our website is designed to help you with this.
How can I see success rates relevant to me?
We show summary information about the type of patients each clinic treats, eg the diagnoses, duration of infertility and age of patients. This may help you identify clinics that treat patients with similar treatment needs to you and also gives some context to the success rates for that clinic.
Female fertility declines with age and this will affect your chance of getting pregnant. We show the success rates for different age groups so that you can see how successful treatment is for an average woman in your age group.
Success rates are broken down into the type of treatment undertaken. With in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI), we also show the outcomes depending on whether you are using fresh or frozen embryos.
If you are using donated eggs in IVF treatment, the success rates are shown for a single all patient category, instead of separate patient age categories.This is because donated eggs come from women aged 35 or younger and it is the age of the woman’s egg used rather than the age of the recipient patient herself that is the main factor in determining the success of treatment.
Data on multiple births (twins and triplets)
Multiple pregnancy is the single biggest risk of fertility treatment to both mother and baby. The birth of a single, healthy child is the safest, most desirable outcome of fertility treatment.
Therefore it is important to look for clinics that have a high proportion of single births, as well as a good overall success rate.
For each clinic we show firstly whether treatment results in a live birth and secondly whether the live birth is composed of a single baby, twins or triplets.
In January 2009 the HFEA introduced a target for clinics that at least 76% of their total live births should be made up of single babies (ie a maximum of 24% multiple live births). This is part of a clinician-led national strategy to try and minimise the risks associated with multiple births from fertility treatment.
For more information about the risk of multiple births from fertility treatment see:
Clinical pregnancy rates
Clinical pregnancy is a pregnancy where an ultrasound scan has shown at least one fetal heartbeat.
Clinical pregnancy rates are used to give you more recent data for clinics as it takes –2 - 3 months to collect this information for a treatment cycle compared to 10 - 12 months to collect information about live birth outcomes.
Clinical pregnancy rates do not provide the full picture of success that a final live birth rate does as not all clinical pregnancies will develop into live births. This information is provided as an additional resource to help you make decisions around your treatment.
Intra uterine insemination (IUI) with partner sperm data
We started collecting data on IUI treatment with partner sperm in July 2007. We only collect data on pregnancies resulting from IUI treatment, not live births.
How old are the success rates published on this site?
The most recent live birth rates may seem like a long time ago. This is because we have to wait for at least nine months after a treatment is carried out to know what the outcome is. We then have to go through a process of verifying the accuracy of the data with the clinics.
We know that patients want access to the most up to date success rate information. Because the HFEA gets clinical pregnancy rate data several months before births data, clinical pregnancy rates can be given for more recent treatments.
As well as the most recent year’s data, we also show data from treatment cycles started in the three previous years. This can give an idea of how consistent the clinic has performed over time. However this should only be used as a guide.
Clinic practices change over time and success rates relating to a period of treatment several years ago may not be a good indication of success rates at the particular clinic today.
How do we get the figures?
The vast majority of overall success rate data published on our website is derived from data about individual treatment cycles and their outcomes given to us by the clinics themselves. Only pregnancy rates for Intra Uterine Insemination (IUI) with partner sperm have been supplied by clinics in pre-aggregated form.
The responsibility is on the clinics to ensure that the data they send us fully reflects all the treatments they carry out and does not contain any inaccuracies or omissions.
The HFEA visits clinics periodically to assess the reliability of their reporting. The HFEA requires each clinic to check the individual cycle and outcome data held by the HFEA against their own medical records for the reporting period, and then to self certify, by signing a document confirming the data they have provided us is correct.
We present a clinic’s live birth rate as either above, below or consistent with the national average live birth rate.
If a clinic’s success rate is consistent with the national average, there is no statistical difference between the clinic and the national average. Any small difference between the clinic and the national average may just be down to chance.
A few clinics will have a success rate that is significantly higher or lower than the national average. This means we can be confident that the difference between the clinic and the national average is unlikely to have occurred by chance.
There are a range of reasons why a clinic may have a higher or lower success rate than the national average. Clinics have different treatment policies and practices. Some clinics treat proportionately fewer or more patients with difficult fertility problems than the national average.
Why do we present the predicted chance of a live birth as a range?
However we also use this data to predict the future chance of a live birth for an average patient who goes to that clinic. This is presented as a range eg, the predicted chance is between 12 – 28%.
Why do we show this as a range instead of a single % figure?
No statistic is absolute. If we present a clinic as having a success rate of 20%, this rate will vary from year to year even if all other factors are kept the same, just because of chance.
By presenting a range we can show how reliable our prediction of the future chance of success at a clinic is.
For example: consider a clinic carried out 100 treatment cycles in 2007. 20 women had a live birth. This is a 20% live birth rate for that year. How likely is it that the clinic could repeat this performance if it treated another 100 women with similar treatment needs under similar clinical conditions the following year? The range gives the answer that the success rate will fall between 12% and 28%.
Why does the size of the range vary for different clinics?
The size of the range is based on how many cycles a clinic carried out in a given year. The more treatment cycles a clinic carries out in that year, the more reliably we can predict how it will perform in the future.
If a clinic carries out a large number of treatment cycles in a given year, we can make a more reliable prediction of how it will perform in the future under similar conditions. This is shown by a smaller range.
If a clinic only carries out a few treatment cycles in a given year, it is hard for us to reliably predict how it will perform in the future under similar conditions. This is shown by a larger range.
Clinic A: 200 out of 1000 treatment cycles in 2007 resulted in a live birth = 20%
Clinic B: 2 out of 10 treatment cycles in 2007 resulted in a live birth = 20%
However because Clinic A carried out far more cycles, we can be more confident when we predict the future chance of success for an average patient at that clinic. This is shown by a smaller range.
Clinic A: the predicted chance of a live birth will fall between 18% - 23%
Clinic B: the predicted chance of a live birth will fall between 3% - 56%
Even though the range may be large, the average chance of a live birth is likely to be towards the centre of the range, not either extreme.
Page last updated: 08 March 2010