15 Eggs Retrieved In The IVF-Cycle Increases Birth Success

13.05.2011

An analysis of over 400,000 IVF cycles 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.

With IVF, a woman's eggs are fertilised with sperm outside the body in a test tube and then placed back inside her womb. The first IVF baby was born in the UK in 1978 and since then, more than four million children have been conceived worldwide using this treatment.

This latest study found a strong relationship between live birth rates and the number of eggs retrieved in one cycle. It showed that the live birth rate rose with an increasing number of eggs up to about 15. It then levelled off between 15 and 20 eggs and steadily declined beyond 20 eggs.

"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," explained one of the authors of the study, Dr Arri Coomarasamy, of the University of Birmingham in the UK.

Dr Coomarasamy and his colleagues analysed data on 400,135 IVF cycles that took place in the UK between 1991 and 2008.

"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.

OHSS is an excessive response by the ovaries in response to hormone drugs administered to stimulate the production of eggs for collection for IVF cycles. Mild and moderate OHSS causes abdominal pain, swelling and sometimes nausea and vomiting. In rare and severe cases, it is a life-threatening medical emergency, with massive ovarian enlargement, fluid accumulation in the abdominal and pleural cavities, and a risk of thrombosis (blood clots).

"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," Dr Coomarasamy explained.

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