IVF or ICSI: Is the More Complex Method Really Better?

For many couples hoping to have children, assisted reproduction is a complex journey involving various treatment options. One of these is ICSI, which is now very commonly used in conjunction with IVF. However, new research raises the question of whether this more complex fertilization method actually benefits all couples.

A large Canadian analysis of 140,252 IVF treatment cycles has reached a remarkable conclusion: For couples in whom no male factor was identified as the cause of infertility, ICSI did not result in a higher cumulative live birth rate than conventional IVF. In the study, the rate was actually 36.3 percent after ICSI compared to 38.5 percent after conventional IVF.

What Exactly is the Difference Between IVF and ICSI?

In in vitro fertilization (IVF), eggs and sperm are brought together in the laboratory. The sperm must fertilize an egg on their own. Fertilization therefore takes place outside the body before the resulting embryo continues to develop and can later be transferred to the uterus.

With ICSI, or intracytoplasmic sperm injection, on the other hand, a single sperm is specifically selected and injected directly into the egg using a very fine pipette. ICSI is therefore not a completely different fertility treatment from IVF, but rather primarily alters the actual fertilization step within an IVF cycle.

This can be particularly helpful when sperm have difficulty fertilizing an egg on their own. The method was originally developed primarily for couples with male-factor infertility. ICSI can also play an important role following a previous IVF cycle in which fertilization was very poor or failed to occur, despite generally suitable conditions.

Why is ICSI Used so Frequently?

The idea behind ICSI sounds convincing at first: If a sperm cell has difficulty penetrating the egg, the embryologist can simply take over this step using technical means. This allows for more targeted support of fertilization.

However, a higher or easier fertilization rate does not automatically mean a higher probability of having a baby. This is precisely where current research comes in. Ultimately, what matters most to patients is not how many eggs are fertilized in the lab, but whether embryos develop from them, a pregnancy occurs, and a healthy child is born in the end.

Although the Canadian study showed a slightly higher fertilization rate with ICSI, there were no corresponding benefits in terms of the number of normally fertilized eggs or the number of usable embryos per egg retrieval. In fact, conventional IVF performed slightly better in this analysis when it came to the cumulative live birth rate.

Large-Scale Study Involving More than 140,000 Treatments

For their study, the researchers analyzed data from the Canadian Assisted Reproduction Registry. Treatments between 2013 and 2022 were included. The analysis encompassed 35,251 cycles of conventional IVF and 105,001 cycles of ICSI in couples without a diagnosed male factor.

The researchers did not merely examine whether an egg was fertilized. An important endpoint was the cumulative live birth rate. This metric takes into account live births resulting from both fresh and frozen embryo transfers that originated from a single egg retrieval. This figure can therefore be more meaningful than simply the success of a single embryo transfer.

The result was surprising: 38.5 percent of treatments with conventional IVF resulted in a cumulative live birth, compared to 36.3 percent with ICSI. The researchers therefore conclude that ICSI showed no advantage in terms of the cumulative live birth rate in cases of non-male-factor infertility.

A New Meta-Analysis also Finds No Advantage

Furthermore, the results of the Canadian study are not isolated. A systematic review and meta-analysis published in 2026 evaluated six randomized controlled trials involving couples without severe male infertility.

Here, too, ICSI showed no advantage over conventional IVF in terms of live birth rate or cumulative live birth rate. The authors rated the evidence for these key findings as high quality but also pointed out several limitations, including the limited number of high-quality studies with live births as an outcome.

When ICSI May Be Appropriate

This by no means implies that ICSI is unnecessary. In cases of severely impaired male fertility, it can be an important treatment option. For example, if there are very few suitable sperm available, or if fertilization failed or was very poor during a previous IVF cycle despite favorable conditions, the direct injection of a single sperm into the egg may be appropriate.

The key point, therefore, is this: ICSI is not automatically a “better” version of IVF. Rather, it is a specialized technique that can offer clear medical benefits under certain conditions.

Why, then, is ICSI also used for couples who do not have a severe male factor? The reasons can be varied. Among other things, the method may seem attractive to clinics and patients because it makes fertilization more technically controllable.

However, current data suggest that a closer look is warranted. In the absence of severe male infertility, the additional technical support does not automatically seem to lead to a higher probability of a live birth. The new meta-analysis therefore also concludes that ICSI should not be used routinely outside of specific indications.

Conclusion

The question, then, is not necessarily “IVF or ICSI—which method is better?” but rather: Does this couple even need ICSI? In cases of severe male infertility, the method can be very valuable. If, on the other hand, there is no severe male factor, the latest data show no convincing advantage over conventional IVF in terms of the probability of a live birth.

The research thus supports a more individualized approach to treatment. The technically more complex method is not automatically the better one—what matters is which treatment is best suited to the specific cause and circumstances of the desire to have children.