Intracytoplasmic Sperm Injection (ICSI) is the most commonly used type of In Vitro Fertilization (IVF) using the woman's eggs after being retrieved from the ovaries by follicle puncture. Today, nearly 90% of IVF cycles are done using the ICSI technique.
It should be noted, however, that classical IVF is almost as successful as ICSI the first time. In fact, the odds of pregnancy depend on other factors, especially on age and egg quality, rather than on the technique used to fertilize the egg.
The different sections of this article have been assembled into the following table of contents.
How to determine ICSI success
To determine the success of the ICSI technique, we can pay attention to several rates, including the pregnancy and the live birth rates. All in all, the ultimate goal is to achieve a successful pregnancy and to deliver a healthy baby.
Nowadays, the pregnancy rate per embryo transfer in ICSI cycles is about 37%, while the live birth rate is 25% approximately. In short, it means that one out of four ICSI cycles lead to the delivery of a healthy child.
If we evaluate the ICSI success rates by age, these figures can vary greatly, given that a woman's ovarian reserve and the quality of the eggs she releases diminish with age.
Factors that influence the odds of success
ICSI is the preferred technique for most embryologists because of the number of advantages that if offers in comparison with classical IVF. However, one should keep in mind that there exist a series of factors that can affect the outcomes of ICSI:
- Expertise of the specialist
- Conditions of the lab and the incubator
- Egg quality
- Egg maturation
- Age and ovarian reserve
- Sperm motility and morphology
- Chromosomal abnormalities in the eggs and/or sperm
- Uterine abnormalities, including endometriosis or uterine fibroids
Some experts have a different opinion as regards the pros of ICSI, considering that standard IVF procedures can reach higher success rates in older women, such as the possibility of creating embryos with a reduced number of chromosomal abnormalities.
In spite of that, a general overview of the results of ICSI over the years has shown that the likelihood of developing a genetic disease in children born by ICSI is similar to that of naturally conceived children.
Want to learn more about the pros and cons of both techniques? Check this out: ICSI Success Rates Compared to IVF Treatment - Which Is Better?
Success rates by age
As mentioned earlier, age is a key factor when it comes to determining the success rates of ICSI procedures. We have split the success rates per cycle into three age groups, as one shall see in the following sections.
Even though the ICSI fertilization rate is 70-85% on average, it should be reminded that fertilization does not translate into a successful pregnancy. The risk of early embryo arrest or miscarriage exists and should be considered when determining the pregnancy success rates of IVF/ICSI.
Taking into account the percentage of positive pregnancy tests obtained per IVF transfer, the success rates of IVF with ICSI by age can be classified into:
- Women aged <35 years
- Success rates of ICSI the first time can be as high as 32%, and can increase to up to 49% in subsequent cycles (cumulative rate) with Frozen Embryo Transfer (FET).
- Women aged 35-39 years
- The pregnancy rate drops to 26% on the first attempt, and the cumulative rate can reach up to 37%.
- Women aged ≥40 years
- The pregnancy success rate is nearly 23% the first time, with a cumulative rate of 20% in subsequent FET cycles.
Indeed, as one can see, age is the most challenging factor for female patients considering IVF/ICSI treatment, to the point that it determines whether the treatment will be successful or not.
Live birth rate
The live birth rate refers to the number of healthy children born after an IVF/ICSI cycle, which is the ultimate goal of every infertility treatment. The success rates by age can be described as follows:
- Women aged <35 years
- 24 percent chance of a live birth per cycle.
- Women aged 35-39 years
- 18 percent chance of a live birth per cycle.
- Women aged ≥40 years
- 7 percent chance of a live birth per cycle.
The live birth rates, as one can see by comparing both graphs, are lower if compared to the pregnancy success rates. Unfortunately, a percentage of ICSI cycles end up in miscarriage.
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FAQs from users
What are the success rates of ICSI? What about IVF?
Fortunately, multiple studies have demonstrated fertilization and pregnancy success rates with ICSI are equivalent to standard insemination by IVF.
In which cases is ICSI used automatically?
ICSI or Intracytoplasmic Sperm Injection is a type of In Vitro Fertilization that is used to fertilize the egg cell. With ICSI, the sperm cell is selected and injected within each one of the eggs collected.
Unanimously recognized indications of ICSI include:
- Severe male infertility: a single sperm per egg cell is enough
- Previous fertilization failure using conventional IVF
- Issues with the oocytes: poor-quality eggs may compromise sperm penetration into the egg cell
- Techniques that involve isolating the egg from the cells that surround it (egg donation, preimplantation diagnosis...)
What are the advantages and disadvantages of ICSI over IVF?
Both techniques are reproductive technologies, and as such, we cannot say that one is better than the other. Actually, it depends on the diagnosis of each couple. In the case of conventional IVF, we put the oocyte in contact with a determined concentration of sperm, so that the sperm itself fertilizes the egg, which resembles natural fertilization to a large extent. In many cases, sperm quality is altered, in which case using the sperm won't be possible. In such situations, we use ICSI. It consists in microinjecting the sperm, which is subjectively selected by the embryologists, into the oocyte.
Does ICSI increase chances of twins?
Yes, there's an increased chance of becoming pregnant with multiples as in classical IVF procedures. To be precise, the risk of a twin pregnancy with ICSI is about 30-35%, and a 5-10% chance for having triplets or more.
What are the success rates of ICSI the first time?
The success of a fertility treatment using ICSI depends on several factors, but especially on maternal age. So you can have an idea, a woman whose ovarian reserve is not severely affected and is able to obtain at least 8 viable eggs in one cycle can reach a pregnancy rate of 37% per embryo transfer, and a live birth rate of 25% following the first attempt.
What are the ICSI success rates with male factor?
In depends on the cause of male infertility. For example, severe male factors such as azoospermia require a testicular biopsy to obtain viable sperms.
The odds of success of ICSI depend on the expertise of the embryologist to select the most viable live sperm out of the ones retrieved from the testis, with good motility and morphology. If sperms with this characteristics were found, the success rates will be similar to those of a cycle with non-affected sperm. The success rates are 22% approximately.
What are the ICSI success rates with PCOS?
The majority of women are able to get pregnant with ICSI in spite of having PCOS (Polycystic Ovary Syndrome), provided that they are not older than 40 years of age. With ICSI, the success rates can be as high as 60%.
What is the IVF/ICSI success rate with PGD?
Suggested for you
The ovarian reserve is an indicator of the egg supply of a woman at a particular stage of her reproductive age. Want to learn more about its relationship to female fertility and how to measure it? Check this out: What Is the Ovarian Reserve?
The number of eggs retrieved after ovarian stimulation influences the success of ICSI. To learn more about the recommended number of eggs to be obtained for IVF, click here: What Is a Good Number of Eggs Retrieved for IVF?
You can learn more about the reasons why a couple may need ICSI treatment by visiting the following post: When Is ICSI Recommended?
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Sociedad Española de la Fertilidad (SEF). Fecundación in vitro o microinyección espermática (FIV/ICSI), y criopreservación de embriones. Documento informativo.
FAQs from users: 'What are the success rates of ICSI? What about IVF?', 'In which cases is ICSI used automatically?', 'What are the advantages and disadvantages of ICSI over IVF?', 'Does ICSI increase chances of twins?', 'What are the success rates of ICSI the first time?', 'What are the ICSI success rates with male factor?', 'What are the ICSI success rates with PCOS?' and 'What is the IVF/ICSI success rate with PGD?'.