IVF success rates may be the trigger to the decision about choosing the IVF clinic. That’s why it’s highly important to realise how are they measured. During this #IVFWEBINARS and Q&A session, Dr Hana Visnova – Medical Director at IVF Cube,
explains how to understand the options for success during the IVF treatment. She describes what the typical statistical methods are and how to compare different results that patients may find on the websites of IVF clinics or in the scientific literature.
Dr Hana Visnova admits that success rates are the information fertility patients are usually most concerned about. All of them want to know what their chances of getting pregnant are. However, we need to specify what the pregnancy rate means. First, it may be understood per treatment commenced – this includes all the female patients who start any kind of hormonal stimulation. Secondly, the pregnancy rate can be related to egg retrieval. Unfortunately, not every patient starting IVF treatment will reach the day of egg retrieval. It depends on her age, hormonal situation and many other factors. There is a huge gap between the number of treatments started and the number of females who achieve their goal of egg retrieval. Thirdly, we can talk about pregnancy rates in terms of the number of women who underwent the embryo transfer. So when talking to a medical specialist, always ask them about their way of calculating pregnancy rates and your own individual chances. If you decide to invest your money, time and – most importantly – emotions, it is crucial to have this knowledge prior to the beginning of any hormonal stimulation.
According to Dr Visnova, when talking about pregnancy rates, we also need to understand how many embryos are used for embryo transfers. There is a number of countries and clinics that perform just elective single embryo transfers (ET). It means the very best embryos are picked-up from a larger group of embryos. This can help to reach higher pregnancy rates compared to single embryo transfers where there are no surplus embryos for better selection. In the countries where two, three or more embryos are used for the transfer, the pregnancy rates are higher, too.
However, Dr Hana Visnova pays attention to the risks of multiple embryo transfers. Remember that you should always consider your safety when you start IVF treatment. And the best pregnancy for every woman is a singleton pregnancy. Only such a pregnancy gives the best chances of an uncomplicated course of pregnancy, uncomplicated delivery and the child’s best health conditions. If you decide on IVF treatment in a clinic accepting 3 or more embryos for transfer, then you must accept a higher risk of potential complications. So, according to Dr Visnova, one should always look for information on how many embryos are transferred to the womb in one treatment cycle.
Additionally, one of the most important prognostic factors is the age of a female. Scientific literature reports pregnancy rates in different age cohorts separately. If you want to know your individual chances of success, always check what age group you belong to. It is obvious that pregnancy rates for 25-year-old girls will differ a great deal from the pregnancy rates in a group of women who are 35-45 years old. Unfortunately, there is a decline in success rates according to the increasing woman’s age.
Understanding pregnancy rates is one thing. Apart from that, we need to know if embryos were genetically tested prior to the transfer. Dr Visnova reminds us that the embryos screened with the use of preimplantation genetic testing methods (PGT-A) always give higher pregnancy chances compared to the not tested ones. In this way, genetically abnormal embryos are eliminated from the embryo transfer. The embryos are more precisely selected, and the success rates go up to 65% (per single embryo transfer). Thus, patients do not lose time on embryos which would never get implanted anyway and shorten their time to achieve pregnancy.
As Dr Hana Visnova explains, there are a few more ways in which success rates are calculated. While the pregnancy rate means how many women get pregnant, the implantation rate refers to the number of embryos that are implanted in the uterus. If we calculate fresh embryo transfers and also consider frozen embryo transfers in the near future, then we speak about the cumulative pregnancy rate. Take home baby rate or live birth rate is the number of children born after successful treatment. The live birth rate also includes twin rates. No matter if there is a singleton or double embryo transfer, they should be calculated as one birth and not two babies born. However, if there are e.g. three embryos transferred and three times a singleton pregnancy, we can speak about the cumulative live birth rate.
Another way in which we can understand success rates is a cumulative oocyte-to-baby rate. In general, it means how many eggs a patient needs to get retrieved (or obtained from the donor) to result in a baby, understood as a successful pregnancy and a delivery. If you have fresh eggs available for the embryo transfer and you belong to the group of patients with a good prognosis or this is egg donation treatment, then you probably need 7.6 eggs to have a baby. But if you use frozen eggs, in egg donation programmes, or do social freezing, then the number of eggs needed to have a good chance of pregnancy is significantly higher – 14 eggs. Of course, the latter does not refer to females above 45 years of age – there, a woman needs about 30 eggs (in case of social freezing) to have a 90% chance of pregnancy.
According to Dr Hana Visnova, pregnancy rate calculations should not include biochemical pregnancies. One can only include pregnancies which are confirmed with the ultrasound. Viable clinical pregnancy means that it is possible to see a gestational sac with a healthy embryo and a heartbeat. The next step is an ongoing pregnancy – when the first trimester was completed and the pregnancy has an excellent prognosis to continue further.
Once you want to understand pregnancy rates, you should also realise that, unfortunately, some pregnancies end with a miscarriage. Most medical complications that result in pregnancy terminations are related to maternal health conditions, her medical history or advanced age.
Finally, Dr Hana Visnova highlights that good cooperation between an IVF clinic and its patients is needed to provide reliable success rates. Medics need the patients to report deliveries and abortions, as well as information on the health condition of children born. Only in this way, IVF clinics can be exact and have complete statistical data available for the next intended parents. This is crucial in order not to underestimate or overstate people’s chances of getting pregnant through IVF treatment.
The Importance of the Embryology Lab in Optimizing Success Rates