Natural insemination (IVF), the process where thousands of sperm are added to an egg in a culture dish to achieve fertilisation, is more likely to lead to a successful pregnancy for older women with infertility than Intracytoplasmic Sperm Injection (ICSI) a new study from the University of Adelaide and Repromed has found.
One in every 25 children in Australia is born by assisted reproductive technologies, with ICSI currently being used to achieve fertilisation in two-thirds of these. ICSI is performed as an additional part of an IVF treatment cycle where a single sperm is injected into each egg to assist fertilisation using very fine micro-manipulation equipment. In older women, where fewer eggs are retrieved in each cycle, it is common practice to perform ICSI in the hope that this will optimise fertilisation rates.
While introduced primarily in Australia for severe male factor infertility, today ICSI is often used in preference to standard IVF insemination in couples without male factor infertility.
University of Adelaide researchers reviewed 10 years of first cycle data from Adelaide IVF clinic Repromed from patients aged over 35 and discovered that, in cases that didn’t involve male infertility, using natural insemination IVF rather than ICSI increased the chance of a having a baby over ICSI by more than 50%.
Lead researcher, Dr Nicole McPherson from the Robinson Research Institute and Freemasons Centre for Male Health and Wellbeing at the University of Adelaide, said the findings supported the use of routine IVF as the preferred insemination technique for older women struggling with infertility when their partner has normal fertility.
“A reason why standard IVF insemination in couples with advanced maternal age and non-male factor infertility may increase their chances of having a baby is because it still allows natural selection of sperm with optimal DNA health,’’ she said.
“With ICSI, sperm even with highest degrees of DNA damage can be chosen and result in fertilisation, but poorer embryo quality and reduced pregnancy rates.”
Alternatively, Professor Kelton Tremellen, Medical Director of Repromed, believes that “removal of the support cells attached to the egg before injecting a sperm (ICSI), a procedure that is not required in natural insemination, may rob the older egg of growth factors secreted by these support cells”.
Professor Tremellen said, irrespective of the underlying cause, the data shows that ICSI should not be used in older women unless sperm quality mandates this treatment.
Dr McPherson said, moving forward, it was important to understand how to increase clinician and patient confidence that standard IVF insemination in women of advanced age is a viable option.
“We suggest that clinics should have a policy of either a split IVF/ICSI insemination in their first cycle to check for the potential for fertilisation and only perform ICSI insemination in subsequent cycles if standard IVF insemination fertilisation rates are below 50%,’’ she said.