On average, a minimum 75% of mature eggs should fertilise after ICSI. Sometimes total fertilisation failure (TFF) or total abnormal fertilisation fertilisation (such as 1PN or 3PN) can occur (in up to 3% of ICSI cases) and cause Low Egg Fertilization Rate.

Why is my Egg Fertilization Rate Low? 

And more importantly, is there anything that can be done about it?

Understanding the exact cause of TFF is extremely difficult. Some of the most common causes are:

Poor Egg Quality:

Once injected, an egg needs to go through certain processes in order to become ‘activated’. ‘Oocyte activation’ renders the egg capable of becoming fertilised. Failure of oocyte activation is one of the most common reasons for failed fertilisation after ICSI, accounting for over 50% of TFF cases.

Egg Maturation Issues:

An egg can degenerate following ICSI if it is post-mature or if the egg matured immediately prior to injection. Eggs falling to achieve good maturation may be due to hormonal stimulation methods which did not suit you.

Sperm Issues:

Failed fertilisation due to sperm factors has been linked to sperm morphology, sperm nuclear morphology, acrosomal factor and sperm chromatin status. Issues with sperm head decondensation can lead to the sperm’s DNA remaining ‘locked’ inside the sperm head and not being released into the egg. This inevitably leads to failed or abnormal fertilisation.

Technical Issues:

A rare cause of TFF after ICSI can indicate poor technical skill of the embryologist – as it is possible for an egg to be damaged by the injection process.

How can my egg fertilization rate be improved?

The life cycle of an egg is long, complicated & prone to errors. By improving your lifestyle & nutrition and supplementing with the correct antioxidants, egg health may be improved. 

The human egg starts its final developmental cycle about 90 days before ovulation, so it’s important for these adjustments to take place during as much of these 90 days as possible.

A change in treatment protocol and/or stimulation medication may also improve your results.

In cases with persistent failed fertilization (after different meds and protocols were used), using assisted oocyte activation (AOA) is currently the only available method to improve fertilization rates. 

Activation can be induced with the use of electrical, mechanical, or chemical stimuli that elevate intracellular concentrations of calcium ions (driving force behind activation). However, these methods work by flooding an egg’s ooplasm (the inside of the egg) with calcium ions that don’t follow the physiological cascade. 

This practice raises concerns, as these chemicals may affect embryo viability and future offspring due to their potential cytotoxic, mutagenic and teratogenic effects.