Identifying the risk of low ovarian response during repeat IVF — implications for fertility treatment provision during the COVID-19 pandemic

The COVID-19 pandemic has resulted in an increased workload for assisted conception clinics worldwide. Factors such as the slower turnaround of cases (due to COVID-19 precautions), the backlog of cases from the time of the first wave, as well as issues with staff resources, may all contribute to delays in accessing fertility treatment. Understandably, fertility guidelines during the COVID-19 pandemic highlight the need to prioritise certain patient groups when offering IVF treatment.

One of these at-risk groups are women with low ovarian reserve (LOR) ie, low egg stores. These women are thought to have below-average chances of having a baby after IVF, particularly if age is also a concern. Consequently, they tend to require repeat IVF cycles, which, during COVID-19 times, can be facilitated through a priority system. Studies have also shown that women's ovarian reserve inevitably declines with the passage of time. For women with LOR, it is reasonable to assume that any further reduction of the ovarian reserve can be particularly detrimental.

But what about women who have already undergone IVF treatment? Should we continue to look at their ovarian reserve for making prioritisation decisions? Or should we look at what happened during the first IVF cycle? Surely, it must be relevant how many eggs were collected. We know from experience that not all women with LOR will produce low egg numbers. The opposite also stands; not all women with normal ovarian reserve (NOR) will produce a satisfactory egg yield.

At Bourn Hall Clinic, we performed an original study that looked at the risk of low ovarian response (having up to three eggs collected) during repeat IVF. We found that three factors can reliably predict performance during subsequent IVF: i) the woman's ovarian reserve, ii) the egg yield from the initial IVF and iii) the time interval between IVF cycles. Unsurprisingly, women who combine LOR and a low initial egg yield have the highest risk of suffering from a low egg yield again (57 percent within one year, 73 percent after one year). This adds to the argument of prioritising women with LOR for IVF.

However, other groups are also at risk. These include women with LOR who manage to achieve a reasonable egg yield initially (4-9 eggs), as well as women with NOR who perform below expectations and, thereby, achieve a low initial egg yield; women in these two groups have approximately a 28 percent chance of a low egg yield within one year, which increases to 44 percent after one year. Interestingly, 55 percent of women who experienced a low egg yield during repeat IVF, had not done so during their initial IVF cycle.

What are the implications of our study for fertility treatment provision in the light of the COVID-19 pandemic? Firstly, prioritisation of certain IVF patients needs to be continually re-evaluated, as expectations may change during the IVF journey. Secondly, focusing exclusively on the woman's ovarian reserve is not an optimal prioritisation strategy for patients who have already started their IVF journey, it will likely disadvantage women with NOR who unexpectedly achieve low egg yields. Finally, the study confirmed that for a good proportion of IVF patients, time delays do matter. Therefore, while going through the COVID-19 pandemic, it is scientifically advisable to use the woman's ovarian characteristics for making prioritisation choices around offering fertility treatment.