Success Rates (ART pregnancy rates or outcomes)

The major problem with success rates is that the average fertility rate for humans is inherently low and therefore any cycle is much more likely to result in failure than success.  Patients undertaking ART treatment have lower fertility than the general population and even though ART increases the chance of conception above that without treatment, unfortunately the most likely outcome for any cycle is still no pregnancy.  Therefore patients should be aware that in order to increase their chances of a live birth they should consider multiple cycles.  

Along with fees, success rates is one of the most confusing aspects of fertility treatment.  Disappointment regarding unsuccessful treatment is a cause of many patient complaints and frustration.

It is the aim of this section of the website to provide a realistic indication of success rates so that patients are more informed about their fertility treatment.  We will do this in two ways:

1. We will present information on the Australian and New Zealand success rates for ART procedures so that patients can gain an idea of the overall pregnancy rates from various treatments.  We will not provide specific information regarding individual fertility clinics, rather the information will provide an overview of Australian and New Zealand clinics.
2. Many Australian fertility clinics market their success rates as being superior to others, however the marketing information can be misleading.  It is the aim of this website to inform patients so that they can interpret the information provided by fertility clinics to gain a more realistic idea of pregnancy rates for ART procedures at each clinic.

For reference we refer to the latest report from the National Perinatal Epidemiology and Statistics Unit (NPESU) entitled Assisted Reproductive Technology in Australia and New Zealand 2016.  Access to this report can be obtained via https//npesu.unsw.edu.au/surveillance-reports.

Areas of Confusion in Reporting Pregnancy Rates

1. Pregnancy rates are low for single cycles.  

Given that the natural pregnancy rate is about 22%, for any 100 women attempting natural conception in a single cycle approximately 22 will achieve a live birth and 78 will not.  Therefore the odds of success in a single cycle is 22 divided by 78 which is 0.28 or odds of 1 to 3.5.

Therefore a woman is three to four times more likely to not be successful as to be successful in any given cycle. 

Although the success rate for natural pregnancy can be reported as 22%, the failure rate is 78%.  

Most ART treatments can be highly successful but not when measured over a single cycle.  Like natural pregnancy, for many patients success is only achieved after multiple or many cycles.

Although success rates for natural conception are low for single cycles, studies have shown that for a population of women attempting natural (non ART) conception 85% will have achieved a pregnancy within 12 months assuming regular frequency of intercourse.   Hence 15% incidence of infertility. (See Read more section for further information.)  Therefore, natural fertility is considered in regards to multiple cycles, and even fertile couples should not expect to get pregnant in a single cycle.

However, when patients undergo ART treatments the treatment is over a single menstrual cycle.  Patients may only complete one or two ART treatment cycles in 12 months or an even longer period of time.  Therefore we are now looking at an outcome as occurring in a single cycle not a series of cycles as is the case for natural conception. 

When patients have ART it is often presented as though the treatment in one menstrual cycle has a high degree of success which it is not true.  Most patients are not informed about the effects of cumulative success.  When the single treatment cycle fails which is the most likely outcome, patients may want an explanation.  The doctor very probably did not promise success but may have failed to explain that success is often only achievable through repeated treatment and perseverance.

2. Success rates are often reported in misleading ways 

Currently in Australia the following definition is provided by the RTAC through the Code of Practice and accreditation process:

Success rates are clinical pregnancy per embryo transfer cycle.

A clinical pregnancy is a pregnancy confirmed by ultrasound where an amniotic sac is seen in the uterus, and also rising hCG is found in blood tests.  Unfortunately a clinical pregnancy does not always lead to a live birth due to miscarriage and also an amniotic sac may not contain an developing embryo (an empty sac).   Therefore patients need to be aware that success rates do not give an indication of live births, only that a early amniotic sac has been formed.

A major misleading factor in reporting success rates is the type of cycle, in this case per embryo transfer cycle.  Many patients regard success rates as being measured on cycles which have been started, however this is not the case.  Only cycles which have progressed to the stage of an embryo being transferred are included in the reported success rates.  This has a huge effect on the success rates as only about half of all IVF/ICSI cycles started progress through to an embryo transfer in that cycle.  This may be due to cancellation of the cycle due to medication complications, or no eggs collected, or no fertilisation, or no embryo develops for embryo transfer.  Therefore patients need to be aware that reported success rates do not give an indication of clinical pregnancy per cycle started.

Fertility clinics may deliberately inflate their success rates

Unfortunately success rates provided by fertility clinics in their marketing strategy do not always adhere to the RTAC definition of clinical pregnancy per embryo transfer cycle.  Some fertility clinics artificially boost their success rates by only including certain groups of patients in their reporting.  For instance patients with lower success rates may be excluded from the success rates reported, such as older patients, and patients with more severe medical conditions may also be omitted to make the pregnancy rate look better.  Also, fertility clinics often do not explicitly say that the success rate is for clinical pregnancy and many patients assume that it is live births which is being reported.

The aim of this section of the website is to provide detailed explanation of reported success rates so that patients can gain a more realistic idea of success rates for fertility procedures.  If patients understand how success rates are being presented by fertility clinics they can make better comparisons between clinics.

3. Success rates are average outcomes.

As with any medical outcomes, the circumstances for an individual may differ markedly from the average and patients must be aware that their likelihood of pregnancy may be very different to the statistical average even when considering patients with similar conditions.

When patients ask, ‘What is my chance of success?’ the answer received is the average chance of success for patients with similar conditions because this is the best that can be provided.  Sophisticated predictor models are in use in some clinics overseas but not in Australia.  Moreover, there is little evidence they provide more accuracy than a simple average.

To explain, the pregnancy rate for natural conception in a population of women is  22% which means that if 100 women had intercourse with their partners over the course of one menstrual cycle then 22 would become pregnant and give birth to a child (or children if a multiple birth) and 78 would not give birth to a live baby.  Therefore the outcome is 22 live births out of 1 cycle each for 100 different women and not 100 natural cycles for an individual woman.  This highlights that all information on pregnancy rates are based on averages of  groups of patients.