Success Rates

Success rates of art

Interpreting Success Rates

Honesty is so important to us, especially when it comes to reporting our rates of success. We prefer to measure our achievements in terms of clinical pregnancy and live birth, rather than positive pregnancy tests alone, with our ICSI and IVF success rates consistently ranking well above the European average.

Assisted reproduction pregnancy outcomes can be measured per cycle started, per egg collection or per embryo transfer.  Merrion Fertility Clinic rates are measured ‘per embryo transfer’.

Rates are measured separately for fresh and frozen cycles. 

  • ‘Fresh’ cycle: transfer of an embryo that was never frozen (cryopreserved)
  • ‘Frozen’ cycle: transfer of an embryo that has been frozen and subsequently thawed for use in a ‘Frozen Embryo Transfer’ (FET)

How Success Rates are Reported

Outcomes of assisted reproduction treatment can be reported as:

  • Positive Pregnancy Test –  2-3 week stage
  • Clinical Pregnancy –  8-12 week stage, visible by ultrasound scan
  • Live Birth –  9 months (full term) or earlier (premature)

Due to the high risk of miscarriage in the early weeks of pregnancy, we measure our success rates based on the later stages: Clinical Pregnancy and Live Birth.

Positive pregnancy tests will always be the highest, then clinical pregnancy rates, then live birth.

It is important to check for this terminology when looking at success rates. ‘Pregnancy rates’ is a vague term, as it is unclear if this refers to a positive pregnancy test or a clinical pregnancy.


Our Success Rates at Merrion Fertility Clinic

Our ICSI and IVF success rates consistently rank well above the European average, as published by the European Society for Human Reproduction & Embryology (ESHRE) and the Human Fertilisation & Embryology Authority (HFEA) in the UK.


One of the main influences on success rates is female patient age, but as you can see from the table above, this is not the only factor. Other influences include diagnosis, previous pregnancy history and medical history.

Overall, our success rate for achieving a clinical pregnancy per embryo transfer for all age groups for IVF and ICSI cycles in 2022 was 41.9%. However, when we look only at Day 5 good or top quality embryos, the rate is 52.6%.

If a patient only has only one embryo, we may recommend a Day 3 transfer, and these embryos can be of mixed quality. Our success rates for Day 3 embryos in 2022 was 25.8%.

On Day 5, sometimes embryos may not be of optimal quality but, if they are still developing, we offer patients the option of having them transferred. We have a policy of allowing lower quality embryos to be transferred because, although the success rates are not high for these embryos, they can and do result in pregnancies. Our success rate for Day 5 fair grade embryos in 2022 was 29%.

In many cases patients will have embryos suitable to freeze, which optimises their cumulative chances of success. Our frozen embryo transfer rate in 2022 was 52.9%. The frozen transfer rate tends to be excellent as only good & top quality embryos are frozen.

FET Success Rates

A frozen embryo transfer (FET) cycle involves thawing frozen embryos and transferring them back to the womb. While success rates with FET cycles have traditionally been slightly lower than fresh cycles, recent advances in embryo freezing techniques have greatly improved outcomes.

In 2022, our clinical pregnancy rates per frozen embryo transfer was 52.9%.

Multiple Pregnancy Rates

At Merrion Fertility Clinic, we believe in optimising your chances of a healthy pregnancy and baby by promoting single embryo transfer (SET) and keeping twin pregnancies at a minimum. Twin pregnancies are much higher risk for the babies and the mother.

We are proud of our low multiple pregnancy rate. In 2022, 6.6% of our pregnancies resulted in a multiple pregnancy. This is compared to a U.K. rate of 6% and a U.S. rate of 6.3% in 2019.

Data reporting 

Merrion Fertility Clinic is the only fertility clinic in Ireland that reports its success rates on a yearly basis in an official clinical publication.

Further information on Clinic activity, fertility treatments and success rates are published in the National Maternity Hospital Annual Report. You can access the Merrion Fertility Clinic section of this report for recent years here.

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