IVF success rates

What is an IVF treatment cycle?

A typical IVF treatment cycle involves the following steps:

1. A woman's ovaries are stimulated by injection of fertility drugs (ovarian hyperstimulation).
2. Oocytes (eggs) are then collected from the woman in a day surgery procedure (under local or general anaesthetic).  This is referred to as either oocyte pick up (OPU) or egg collection.
3. The eggs are then fertilised - this may involve intracytoplasmic sperm injection (ICSI) where  a single sperm is injected into each egg to assist fertilisation.
4. After maturation one or more fresh embryos may be transferred to the woman's uterus, this is known as a "fresh embryo transfer").
5. If there are other embryos they can be frozen and may be transferred at a later date.  This procedure is known as a "frozen embryo transfer" or FET.  After all the fresh and frozen embryos from the initial stimulated cycle have been used the IVF treatment cycle is considered complete. 

How is the success of IVF measured?

When it comes to IVF outcomes there is no currently agreed ‘standard’ for reporting success rates.

Often complete IVF treatment cycles can consist of multiple embryo transfers from the one egg collection. Sometimes IVF success rates are quoted for this complete IVF cycle. It should be noted that success rates reported this way will therefore be higher than success rates reported per embryo transfer.

At Queensland Fertility Group we want to give you a realistic understanding of your chance of success for each embryo transfer.  Therefore we normally report IVF success rates per embryo transfer in two ways.  Firstly as clinical pregnancies per embryo transfer and secondly as live births per embryo transfer. Sadly, not all pregnancies result in a live birth which is why we also report births per embryo transfer. (Note: A pregnancy is deemed a “clinical pregnancy” if it has been confirmed by the birth of a baby, a pregnancy sac on an ultrasound scan, or proof of pregnancy tissue from a miscarriage or ectopic pregnancy)

These statistics measure the success rate from the point a patient reaches the stage of an embryo transfer. Sadly, for some women no eggs will be collected. So it is important to note that for some women their treatment cycle will not result in an embryo transfer.  Additionally sometimes embryos fail to develop and therefore there can be no embryo transfer.

When you are looking at the statistics it is necessary to understand exactly which stage of the IVF treatment cycle is being reported. It is also important to consider that other factors will contribute to IVF outcomes.  For example:

• A woman's age is the most important factor determining IVF success rates. When you look at IVF success rates you should be sure you understand exactly what is being reported, (as per above), and also that the results are for women of the same age group.  If all age groups are grouped together i.e. only the total clinic results are reported, it may be that the group of patients is older or younger compared to other clinics. They may also send their more difficult cases to a different clinic.
• If you are unsure you should always ask questions, and we encourage you to do so. For example, is more than one embryo transferred at a time, and if so how often? Success rates can appear higher if multiple embryos are transferred together. If you are looking at US rates you may think they seem higher – but a key factor in this is that they often transfer more than one embryo per transfer. We have strict policies regarding the number of embryos transferred at Queensland Fertility Group.  This is because with more than one embryo being transferred there are increased health risks to the patient arising from multiple births, low birthweight and premature births.
• Make sure you check whether the data includes procedures like ICSI, or includes frozen embryo transfers or only 'fresh'.