Success rates are percentages that show the chances of getting a pregnancy offered by different assisted reproduction treatments. They can vary depending on each centre and on the technique, but, in general, high values indicate that the centre works efficiently and offers good results.
Nevertheless, to interpret them correctly, you have to «read the fine print» and take into account what exactly they refer to, since each centre can present them in the way that best suits them and, therefore, they are not always comparable.
In this post, Dr. Buenaventura Coroleu, a consultant of Dexeus Mujer’s Reproductive Medicine Service, tells us what is important to keep in mind to make a good reading.
8 keys to interpreting success rates correctly
- They are global data, they do not indicate your real possibilities. These are general figures, which calculate an average based on the total number of patients attended by each centre and the results obtained. They do not indicate, therefore, what your real probabilities will be, but they can be used as a guide to know which techniques offer the best results and if the centre works efficiently.
- What time of pregnancy do they refer to? Another important aspect is whether the data refers to the percentage of confirmed pregnancies at the beginning of gestation (positive Beta hCG test), at 7-8 weeks (pregnancy confirmed in a clinic visit by ultrasound and detection of the foetal heartbeat), or to children born (total percentage of pregnancies culminating in the birth of a baby). Biochemical pregnancy rates (positive beta only) are always higher than 7-8 weeks and births, as not all positive pregnancy tests result in the birth of a baby.
- Patients served by each centre. The greater the volume of patients served by each centre, the better, because their results have a more global value.
- Profile of the patients. The success rates of a clinic are determined in part by the type of patients being treated in that centre, the maternal age, and the various factors of infertility. If a centre has a significant volume of elderly women and complex cases, it is possible that, although it works efficiently, its success rates are somewhat lower, since the chances of conceiving decrease with increasing age, and the risks of abortion and other complications associated with pregnancy are higher in elderly patients. If, despite attending a significant volume of elderly women and complex cases, it maintains good numbers, this means that it works very well.
- See if the indicators are broken down by age group. Success rates calculate an average based on the total number of patients served by each centre, so in order to have a more accurate and realistic idea it is important that the centre offers these results broken down by age group.
- Results at the first attempt or cumulative rate. Likewise, it must be considered whether the percentages presented by the centre indicate the probability of achieving a pregnancy on the first attempt or after several consecutive attempts (cycles or treatments), which is called the “cumulative rate”. Many centres highlight the cumulative rate (percentage after multiple attempts) to show higher success rates.
- The chosen technique plays a role. Not all assisted reproductive treatments offer the same results. In in vitro fertilization (IVF), success rates vary according to maternal age, which determines the quality of the eggs, and increases significantly if more than one treatment is performed. Likewise, in elderly women, egg donation treatments tend to offer higher success rates than those using the patient’s own eggs (they are eggs of higher quality). And artificial insemination tends to have lower success rates than IVF, since fertilization is «in vivo» and is what would correspond to general fertility
- Selective embryo transfer (SET) is a quality indicator of the centre. The best marker of efficiency of assisted reproductive techniques is the birth rate obtained in each centre. But evaluating the possibility of success it is always necessary to assess the number of embryos transferred in each treatment. If a centre transfers more than one embryo, it can increase the pregnancy rate at the cost of increasing the multiple pregnancy rate, with the possibility of more complications during pregnancy and delivery. That is why selective transfer of a single embryo (SET) is a quality indicator of the centre.
We hope you’ll find this information helpful!
Remember: if you want to know what your real chances are of achieving a pregnancy, you should ask for an individualized assessment since there are different factors and personal circumstances that can influence the success of the treatment.
