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  • Troubleshooting Low IVF Fertilisation Rates | with Angela Hywood

    December 04, 2023 4 min read

    One of the most disheartening outcomes of an IVF cycle is a low fertilisation rate.

    I wanted to share some information and resources from the troubleshooting low fertilisation rates, to help you figure out what to do next if this happens to you.

    What Causes Poor Fertilisation?

    In a typical IVF cycle, around 70-75% of eggs will successfully fertilise to become a day 1 embryo. Some couples have a much lower fertilisation rate, for reasons that are not well understood. Intracytoplasmic Sperm Injections (ICSI) can sometimes improve fertilisation rates, (however it can risk damaging eggs) but the problem may occur even with ICSI, and this can be a very difficult problem to solve.

    Potential causes for a low fertilisation rate include immature eggs, egg quality, and sperm quality.

    Culprit No. 1: Immature eggs

    An IVF cycle can result in immature eggs if the trigger shot is performed when the follicles are too small. Studies have reported higher fertilisation rates when follicles are at least 16 mm before trigger[1].

    In other cases, the trigger may have been performed at the correct time, but your eggs may be unable to complete the final maturation process because of hormonal issues. These hormonal issues are typically those characteristics of PCOS, such as high testosterone or insulin resistance. High testosterone can result in immature eggs that are unable to fertilise, even with the correct timing of the trigger. This scenario is more likely if you have many eggs retrieved, or you have a high BMI, or high fasting insulin.

    When these hormonal issues are the culprit for immature eggs, you can often improve the fertilisation rate significantly through dietary changes and supplements that address insulin sensitivity (such as myo-inositol).

    Culprit No. 2: Sperm Quality

    Sperm quality should be suspected in any case of poor fertilisation, particularly if sperm DNA fragmentation is high or hasn’t been tested.

    My golden rule - NEVER EMBARK ON IVF BEFORE DNA FRAGMENTATION HAS BEEN TESTED, even if other sperm parameters look fine.


    The DNA integrity is a huge factor in IVF success. If DNA fragmentation is over 15%, you’ll need to back up and do 3 months male preconception health care to improve DNA integrity. Sperm DNA integrity is crucial for fertilisation and development of healthy baby. Sperm DNA fragmentation (SDF) can be caused by extrinsic factors (i.e., heat exposure, smoking, environmental pollutants, and poor diet, nutritional deficiencies, inflammation) as well as intrinsic factors (i.e., defective germ cell maturation, and oxidative stress. Compelling evidence demonstrates that oxidative stress (often drive by toxins and inflammation) is a major contributor to male infertility.

    Many clinics claim that ICSI circumvents all issues with sperm quality, but the data shows that even with ICSI, men who have both abnormal motility and abnormally high DNA fragmentation tend to have lower fertilisation rates [2]. If any semen analysis parameters are abnormal, it may be worth doing further testing, including DNA fragmentation analysis, male microbiome testing, and checking for varicocele. The sperm quality supplements can also significantly improve DNA fragmentation, by preventing oxidative stress.

    If a couple’s fertilisation rate is low, the male partner should do everything possible to improve sperm quality (including the supplements, nutrition, and lifestyle changes) because not all aspects of sperm quality show up in testing. In addition, even if the cause of low fertilisation is egg quality, it is important to optimise sperm quality to make up for any issues on the female side, since the egg may not be able to perform the usual repair processes to typical levels of DNA fragmentation in sperm.

    Culprit No. 3: Egg Quality

    Egg quality is the final possible explanation for a low fertilisation rate, but this particular issue seems to be more difficult to address than other egg quality issues.

    You may need to implement strategies for improving egg quality and the advanced strategies for addressing low ovarian reserve and chromosomal errors, of which there are a lot, including NAD+, NAC or glutathione, NRF2/ ARE pathway modulation botanicals , lipoic acid, professional grade prenatal, CoQ10, at time, hormones such as DHEA and melatonin.

    Studies have reported lower fertilisation rates in women with autoimmune antibodies, particularly anti-thyroid, anti-nuclear, and anti-phospholipid antibodies [3][4]. It is worth getting a blood test for these antibodies if you have not already. Initial research suggests that strategies to regulate the immune system (such as steroids) can improve outcomes in subsequent IVF cycles, including a higher fertilisation rate. This is known as the sub-specialist field of Reproductive Immunology.

    Another option to consider is supplementing with myo-inositol, particularly if you have high FSH. Myo-inositol is typically used for those with insulin resistance, but even without insulin resistance it can sometimes improve the fertilisation rate, likely by helping eggs to become more sensitive to FSH. The typical dose is 4 grams per day, half in the morning and half at night.

    [1] Comparison of fertilization, cleavage and pregnancy rates of oocytes from large and small follicles
    [2] Predictive value of the sperm DNA fragmentation index for low or failed IVF fertilization in men with mild-to-moderate asthenozoospermia
    [3] The Relationships among Plasma Fetuin-B, Thyroid Autoimmunity, and Fertilization Rate In Vitro Fertilization and Embryo Transfer
    [4] Antinuclear antibodies in follicular fluid may reduce efficacy of in vitro fertilization and embryo transfer by invading endometrium and granular cells
    For help with troubleshooting other issues that can come up in IVF cycles, book an appointment for your personalised IVF support treatment plan with  book a consult with Angela here.
    Naturopath and Founder of Floralia Wellness & Apothecary, Angela Hywood, has been specialising in women’s health, hormones and fertility for over 25 years.

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