Fertility 2019: Managing unpredictability in human biology

Human reproductive biology is enormously fascinating and at times equally frustrating. This is primarily due to the complex interaction of a myriad of signals and responses necessary to achieve pregnancy. Not only is there variability in response to IVF treatment between individuals but also from one cycle to the next in the same individual.

That is why at Bourn Hall the treatment is tailored to each individual and to each cycle.

We apply all our experience and scientific knowledge gained over the past 40 years.

Consideration is given to various factors (BMI, age, ovarian reserve etc) in deciding the type, dose and duration of drug treatment as well as the variety of laboratory techniques needed.

Predicting outcome

A lot of the information patients receive is based on the observed behaviour of groups of patients with similar characteristics. This information is good at predicting the likely outcome.

However biology being biology means that the result for an individual can vary by some margin from the statistical mean. The aim of our clinical research is to assess the variability and if possible reduce it.

Variation in ovarian response

An example is a recent study of over 2500 patients in our database which concludes that natural variations in the ovaries have a much greater impact on performance than previously thought. Adjusting the drug dose for subsequent cycles of IVF treatment does not always produce the anticipated result.

Dr Thanos Papathanasiou, our Regional Lead Clinician, comments about the findings to be presented in a poster prepared for Fertility2019the Fertility2019 conference in January. He says: “It is not unusual for patients to have a paradoxical or contradictory ovarian response for the second cycle, for example a lower stimulation dose can produce a higher egg yield.

We reviewed the results from over two thousand patients, comparing the drug protocol and egg yield for the first and subsequent cycles of treatment and concluded that natural variations in the ovary account for unexpected ovarian response during treatment. By using the patients as their own controls it was found that in only half of the cases did the ovaries perform as predicted in a second cycle.”

Dr Papathanasiou concluded: “The most interesting finding was that in 9-17 per cent of cases women experienced a paradoxical ovarian response, where adjusting the drug dosage had the opposite response to that expected.

We know there is huge variation in the quality and quantity of sperm produced and now this study shows that egg production is also highly variable.  Only by tailoring our treatment to the individual will patients have the best chance of success.”

Dr Papathanasiou will also be presenting “The risk of ‘de novo’ poor ovarian response during repeat IVF: Results of an externally validated prediction model based on more than 4,000 women” on  Friday 4th January 2019 at 14.20 in the short paper session at Fertility 2019.

We will publish further details on our fertility insights blog early in the new year.


Fertility2019 is at the ICC Birmingham from 3-5th January 2019 and organised by the Association of Clinical Embryologists, British Fertility Society and the Society for Reproduction and Fertility.

More information fertilityconference.org/programme

The Fertility Insights section on our blog describes other research at Bourn Hall

Details of publications produced by Bourn Hall

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