IVF success rates

What is an IVF treatment cycle?

A typical IVF treatment cycle involves the following steps:

1. fertility drugs are injected to stimulate a woman's ovaries (ovarian hyperstimulation);
2. eggs (also called "oocytes") are collected from the woman (sometimes referred to as "oocyte pick-up" or OPU), this is a day surgery procedure conducted under local or general anaesthetic;
3. the eggs are then fertilised and matured. This may or may not involve other processes such as ICSI (intracytoplasmic sperm injection, a process in which a single sperm is injected into each egg to assist fertilisation using very fine micro-manipulation equipment) or Digital High Magnification sperm selection (which can assist men with DNA damage in their sperm);
4. one or more embryos may be transferred to the woman's uterus (a "fresh embryo transfer"); and
5. other embryos may be frozen and transferred later (a "frozen embryo transfer" or FET). An IVF treatment cycle is considered complete once all fresh and frozen embryos from the initial stimulated cycle have been used.

How do you measure IVF success?

Sometimes IVF success rates are quoted per complete IVF collection and treatment cycle. A full IVF collection and treatment cycle can involve multiple transfers of embryos collected from the one egg collection. Success rates measured this way will therefore naturally be higher than success rates measured per embryo transfer.

At IVFAustralia, we most often measure IVF success rates as clinical pregnancies (a pregnancy confirmed by a blood test and ultrasound scan, usually at around 6-8 weeks) per embryo transfer. Sadly, not every pregnancy will carry to a live birth, so we quote live births per embryo transfer as well as clinical pregnancies per transfer. We report our success rates per embryo transfer as we want to give you the most realistic understanding of your chance of success following each individual embryo transfer.

However it is important to understand that not every treatment cycle will result in an embryo transfer, for some women, no eggs will be collected, and, sometimes after eggs have been collected, there may be no transfer because embryos have not developed.

It is therefore important to understand what part of the IVF treatment cycle a particular statistic is measuring. Even after you check this, there are other factors that need to be understood before you attempt to compare IVF success rates. For example:

• the most important factor determining IVF success rates is a woman's age. When comparing IVF success rates, as well as checking what is being measured, check you are comparing rates for women of the same age. If 'whole of clinic' rates are quoted, consider whether the clinic might, overall, have older or younger clients than average - or do they perhaps send their more difficult cases to a different clinic altogether?
• Ask how often a clinic transfers more than one embryo with each transfer. More embryos per transfer may make success rates appear higher (this is a key reason some US rates appear higher than ours), but IVFAustralia rarely performs multiple transfers, as it can also increase the risks of multiple births, low birth weight and premature births.
• Check whether the data includes processes like ICSI, or includes frozen embryo transfers or only 'fresh'.