Study finds association between the number of eggs and live birth in IVF treatment
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An analysis of over 400,000 IVF cycles in the UK has shown that doctors should aim to retrieve around 15 eggs from a woman’s ovaries in a single cycle in order to have the best chance of achieving a live birth after assisted reproduction technology.
The study, which is published online in Europe’s leading reproductive medicine journal Human Reproduction, found that there was a strong relationship between live birth rates and the number of eggs retrieved in one cycle. The live birth rate rose with an increasing number of eggs up to about 15; it levelled off between 15 and 20 eggs, and then steadily declined beyond 20 eggs.
One of the authors of the study, Dr Arri Coomarasamy, said: “This is the first study to look at the association between the number of eggs and live births. Some smaller studies have reported previously on the association between egg numbers and pregnancy rates, but not live births. This is also the first study to devise a graph that can be used by patients and clinicians to estimate the chances of a live birth for a given number of eggs.”
Dr Coomarasamy, a Clinical Reader and Consultant in Reproductive Medicine and Surgery at the University of Birmingham (UK), and his colleagues analysed data from the UK’s Human Fertilisation and Embryology Authority (HFEA) on 400,135 IVF cycles that took place anywhere in the UK between April 1991 and June 2008. As live birth rates have steadily improved during this period, the researchers used data from 2006 to 2007 to create a predictive model that most closely reflected current practice. Using the model, they created a mathematical graph, called a nomogram, which shows the relationship between women’s age, the numbers of eggs retrieved and the predicted live birth rate. Now patients and clinicians can use the nomogram when making decisions about the degree of ovarian stimulation required to achieve the optimum number of eggs for a live birth.
“Our data show that around 15 eggs may be the best number to aim for in an IVF cycle in order to maximise the chances of a live birth while minimising the risk of ovarian hyperstimulation syndrome (OHSS) which is associated with a high number of eggs, usually over 20,” said Dr Coomarasamy. “Mild stimulation protocols aim to retrieve less than six to eight eggs; a standard stimulation should aim for 10-15 eggs, and we believe this is what is associated with the best IVF outcomes; when the egg number exceeds 20, the risk of OHSS becomes high.”