06 June 2011
ByAppeared in BioNews 610
A US fertility clinic has issued a press release warning against simplistic interpretations of a recent report on IVF success rates.
The statement from New York's Center for Human Reproduction (CHR) responds to a study published in May, which found women undergoing IVF from whom 15 eggs were retrieved had the best chance of a live birth. The study spurred the headline '15 eggs is the perfect number needed to achieve a live birth after IVF'.
Dr Norbert Gleicher, Medical Director of CHR said the headlines oversimplify the data published in Human Reproduction (and reported in Bionews 607). 'Assuming that patients receive reasonable ovarian stimulation for IVF', he said, 'the number of retrieved eggs is only a reflection of the patients' ovarian reserve'.
Ovarian reserve describes how many eggs a woman's ovaries can provide. This can vary depending on her age or health. A woman's ovarian reserve affects how easily her eggs can be retrieved after her ovaries are stimulated to produce eggs during IVF.
Patients could be misled by the suggestion that 15 eggs is always the 'perfect number' to aim for in IVF treatment, Dr Gleicher says. For example, women over 40 will usually produce fewer eggs than young women with polycystic ovary syndrome.
'Technically, ovaries cannot be stimulated towards production of a specific number of eggs', said Dr David Barad, Clinical Director of IVF at CHR. He added: 'If the number of eggs, instead of ovarian reserve, were the true determinant of live birth chances, we could simply stop retrieving eggs when we reach that specified number. This, however, would only increase risks to patients. Perfect oocyte numbers, therefore, cannot really be acted upon'.
A study by CHR published in Fertility and Sterility found levels of anti-Muellerian hormone (AMH), which represents the ovarian reserve, above 1.05ng/ml led to the 'best live birth chances at all ages'.
They say the Human Reproduction study supports their finding that the ovarian reserve offering the best chance of live birth is the same for women of all ages.