Understanding ICSI Success Rates: What You Need to Know
For around half of heterosexual couples who are having problems conceiving, the cause of infertility is sperm-related. Intracytoplasmic sperm injection (ICSI) is one of the most advanced fertility treatments available today for couples experiencing male infertility.
Unlike conventional IVF, where sperm and eggs are mixed in a dish for natural fertilisation, ICSI bypasses allowing for a single healthy sperm to be injected directly into an egg, increasing the chances of fertilisation in cases where sperm motility, quality or quantity are a concern.
According to NICE guidelines for infertility ICSI is recommended for couples where:
There is severe male factor infertility
Previous IVF cycles have resulted in low or failed fertilisation
Sperm has been retrieved surgically (from the testicles or epididymis)
You can find out more about the types of male fertility challenges ICSI is a good fit for, as well as the costs and risks involved in our blog What is ICSI?. But if you’re considering ICSI as part of your fertility treatment, understanding the factors that influence its success rates can help you feel more informed and prepared as you navigate the process, so read on.
What Affects ICSI Success Rates?
Success rates for ICSI depend on a variety of factors, including maternal age, embryo quality and underlying fertility issues.
1. Female Age
The most significant factor influencing IVF success rates (including ICSI) is maternal age. Younger women particularly those under 35 tend to produce higher-quality eggs, leading to better embryo development and implantation success. As a woman’s age increases, the number of viable eggs decreases, and the chances of successful fertilisation drop accordingly.
2. Sperm Quality
Although ICSI can overcome many sperm-related barriers, the success rate of ICSI may be lower when male fertility issues are more pronounced. Severely damaged sperm may still fail to fertilise an egg or lead to poor embryo development. If male infertility is severe, such as in cases of azoospermia (no sperm), the success of ICSI may depend on the availability of sperm for collection, often requiring surgical extraction. Although ICSI can overcome many sperm-related barriers, including low sperm count or high levels of antibodies in the semen, the success rate of ICSI may be lower when male fertility issues are more pronounced.
3. Egg Quality
The quality of the eggs being used also has a direct impact on the outcome of the procedure. Healthy, high-quality eggs have a higher chance of being successfully fertilised with ICSI. In women with conditions like polycystic ovary syndrome (PCOS) or diminished ovarian reserve, egg quality can vary and may affect the chances of successful fertilisation.
4. Embryo Quality & Freezing Embryos
Once the sperm is injected into the egg, the resulting embryo’s development is another critical factor. The embryo’s health, including its genetic makeup, can impact its ability to implant and develop into a pregnancy. Embryo screening, such as preimplantation genetic testing (PGT), can be an option for some people to help ensure the best chance of success. If multiple high-quality embryos are obtained, excess embryos can be frozen for future use. This increases cumulative pregnancy rates without requiring additional ovarian stimulation cycles but, of course, increases the cost of IVF treatment.
5. Uterine Health
A receptive endometrium (the tissue that lines the uterus or womb) is essential for successful implantation. Conditions like fibroids, endometriosis, or thin uterine lining can negatively affect success rates.
6. Lifestyle
Smoking, excessive alcohol consumption, high BMI and poor diet can lower fertility potential for both men and women. Making lifestyle changes before undergoing fertility treatment can enhance chances of success.
What Are the Success Rates for ICSI?
Success rates for ICSI vary significantly across fertility clinics and are influenced by factors like the ones mentioned in the previous section. Some fertility clinics report success rates of between 60% and 80%.
However, on average, ICSI success rates align closely with conventional IVF success rates. In fact they are so similar that the Human Fertilisation and Embryology Authority (HFEA) doesn’t publish separate statistics.
According to HFEA fertility data from 2022:
Women under 35 have an average of 42% live birth rate per IVF/ICSI cycle
Women aged 35-37 have around a 35% success rate
Women aged 38-40 have approximately a 26% success rate
Women over 40 typically have a 10-15% success rate, declining with age
Is ICSI more successful than IVF?
The chances of having a successful pregnancy are the same with ICSI and IVF and, just like with traditional IVF, there are no guarantees that using ICSI will result in successful fertilisation or birth. Although some clinics routinely use ICSI in most patients, it has not been shown to increase success rates in couples where male factor infertility isn’t the apparent cause of their inability to conceive. Moreover, if IVF treatments have been unsuccessful in the past due to immature eggs, then ICSI will not likely give you increased results.
How Long Does It Take to Get Pregnant with ICSI?
It is important to note that ICSI itself does not guarantee pregnancy but improves fertilisation rates when sperm-related infertility is a factor.
The timeline for pregnancy with ICSI is similar to that of standard IVF. A complete cycle typically takes about 6-8 weeks and incorporates the following stages:
Ovarian stimulation
Egg retrieval and sperm collection
ICSI fertilisation and embryo culture
Embryo transfer
Pregnancy test
Some couples may conceive on their first attempt, while others may require multiple cycles.
Fertility Checks and When to Consider ICSI
Before pursuing ICSI, couples typically undergo fertility checks to determine the cause of infertility. Common fertility tests include:
Semen analysis (to assess sperm count, motility and morphology)
Hormonal tests (to check ovarian reserve and reproductive health)
Ultrasound scans (to evaluate the uterus and ovarian follicles)
Genetic screening (if necessary)
If male infertility is identified as a primary issue, ICSI may be recommended as part of the treatment plan.
What can I do to prepare my body for ICSI and give the procedure the best chance of success?
Lifestyle Modifications and General Health Preparation:
Diet and Exercise: Eat a balanced diet, stay hydrated and engage in regular light exercise. Avoid extreme weight loss or gain.
Quit Smoking and Alcohol: Both partners should avoid smoking, excessive alcohol consumption and recreational drugs as they can negatively affect fertility.
Supplements: Women may be advised to take folic acid, and both partners may be advised to take antioxidants or other vitamins that promote fertility.
Stress Management: Fertility treatments can be stressful and emotionally demanding so it’s important to manage that with relaxation techniques such as meditation or yoga and consider counseling, support groups and talking to a fertility specialist to manage expectations and emotions.
What are the risks of ICSI?
ICSI may carry slightly more risk than conventional IVF treatment including:
There is a less than 5% chance chance that some eggs could be damaged during the insertion of the needle
An increased risk of miscarriage because the technique uses sperm that would not otherwise have been able to fertilise an egg.
You are more likely to have a baby with a chromosomal abnormality when conceiving with ICSI compared to having sex. Sex chromosome abnormalities are linked to a higher risk of; miscarriage or your child having learning disabilities or heart issues.
Getting help and support
ICSI can be a highly effective fertility treatment, particularly for couples facing male infertility. If you’re considering ICSI as part of your fertility journey, it’s essential to have a candid conversation with a fertility specialist about your specific case and undergo a fertility check to help determine if this treatment is the right path for you and the best approach for achieving a successful pregnancy.
If you have more questions about ICSI or getting support with your fertility journey in general, then join The IVFN monthly events, Safe Space and Ask The Experts sessions, to help you make informed fertility choices.