St Mary's Hospital

Find out a clinic’s IVF birth rates for:

• Births per embryo transferred
• Births per egg collection procedure

As well as the clinic’s multiple birth rate.

Whatever statistic you look at, it can’t tell you your individual chance of success (only your doctor can do that), but each statistic gives you an overall view of the clinic’s performance.

Births per embryo transferred

Births per embryo transferred is calculated using the number of births (twins or triplets are counted as one birth) divided by the number of embryos transferred, shown as a percentage, in a clinic over 12 months.

This statistic is not usually used to show outcomes over more than one IVF cycle (known as a cumulative success rate) because it counts embryo(s) transferred as a single event.

See the clinic’s rate below.

Find out more about this statistic here.

Births per egg collection procedure

Births per egg collection procedure is calculated by using the number of births (twins or triplets are counted as one birth) divided by the number of egg collection procedures that took place in a clinic over 12 months, shown as a percentage, over a two-year period.

Births per egg collection procedure can be used to show outcomes from all embryo transfers from the same egg collection (known as a cumulative success rate).

See the clinic’s rate below.

Find out more about this statistic here.

Multiple birth rates

For some people, having twins may seem like a wonderful thing, but multiple pregnancies are less safe for both patients and babies. That’s why we set a target for all clinics to have a multiple birth rate of 10% or lower – as of 2023 this has fallen to 3.4%, one of the lowest rates in the world.

See the clinic’s rate below.

For more, see the detailed statistics where you can look at other data.

More about the statistics

Births per embryo transferred

We show births per embryo transferred as it promotes embryo transfer practices that minimise the chances of multiple births, which carry health risks for the babies and the patient.

Births per embryo transferred accounts for cases where multiple embryos are transferred in the same procedure but does not include the outcomes of patients who do not reach embryo transfer stage.

Please note: This includes outcomes from embryos transferred for fresh and frozen embryo cycles. PGT-A cycles and donor egg cycles are excluded, to find data for these go to the detailed statistics section.

Births per egg collection procedure

We show births per egg collection procedure as it’s close to the start of the patient journey and a stage that the majority of fresh embryo cycles that patients undergo will reach.

Because of the way births per egg collection procedure is calculated, it includes both fresh and frozen embryo transfers from the same egg collection.

Please note: This includes all egg collection procedures for fresh and frozen embryo, and PGT-A cycles. Donor egg cycles are excluded, to find data for these go to the detailed statistics section.

National average

It may be tempting to rely solely on success rates, but the most important thing to focus on is whether the clinic’s results are consistent with the national average. Try not to read into differences of a few percentage points above or below the national average, as these are often down to chance rather than being a reflection of a clinic’s abilities.

Reliability range

The reliability range shows how confident we are that a clinic will repeat its success rate in the future – the narrower the range, the more confident we can be. Large clinics normally have a narrower reliability range. That’s not because their data is more accurate but because their rate is less likely to be affected by small changes in the number of births in one year. Small clinics aren’t worse, but their success rate is more likely to be affected by these kinds of changes.

Why are donor egg or PGT-A cycles not included in all these statistics?

Donor egg cycles:

It could unfairly advantage clinics that carry out above average numbers of donor egg cycles because the chance of having a baby with IVF using donor eggs is generally higher compared with IVF using a patient’s own eggs, particularly if they are older than 38, have poor quality eggs, or produce a low number of eggs. This is because the health and age of the egg influences the chance of having a baby. More information about treatment with donor eggs can be found here.

PGT-A cycles:

PGT-A is classed as a treatment add-on by the HFEA. Evidence shows that for most patients starting treatment, it does not improve the chances of having a baby due to the fact it can often reduce the number of embryos available for transfer. For more information about PGT-A see our add-ons page.

With PGT-A, embryos are chosen by looking for abnormalities in their chromosomes (as embryos that appear to have missing, or extra, chromosomes have less chance of developing into a baby). Patients having embryos transferred with a normal chromosome number may have a higher chance of having a baby from that particular embryo. So, including PGT-A in the birth rate per embryo transferred could mean that clinics that carry out above average numbers of PGT-A cycles could have a higher overall rate, because only a certain number of embryos will have been selected, which is why it has been excluded from the births per embryo transferred statistic.

PGT-A occasionally leads to the exclusion of an embryo that may have developed normally. This means, while the chance of a baby per embryo transferred may be higher, if we look at the chance of having a baby for each cycle of treatment started, it may be lower. PGT-A is, therefore, included in the births per egg collection statistic as it gives a true indication of the chance of a live birth per egg collection as some patients having PGT-A may not have an embryo to transfer or have reduced numbers of embryos to transfer.

Detailed Statistics

Our detailed statistics page allows you to tailor your search to better reflect your personal circumstances. Remember, the more precisely you specify your treatment options, the smaller the numbers of past patients and the potentially less reliable the results.

Our detailed statistics allow you to search for more age groups, and to look at pregnancy and birth rates in more detail.