A review of IVF procedures undertaken in the last ten years at the Mayo Clinic in Minnesota, US, has shown that it makes no difference to success rates whether frozen or fresh sperm is used. The results of the study were presented last week at the Annual Scientific Meeting of the American Urological Association in San Francisco.
The researchers reviewed 2,039 IVF cycles that took place at the clinic between 1993 and 2003. Fresh sperm was used in 1580 cycles and frozen sperm in 309 cycles. The overall outcomes of IVF using frozen and fresh sperm were compared, as well as comparative outcomes for various methods of sperm retrieval, including MESA (microsurgical epididymal sperm aspiration), TESE (testicular sperm extraction) and electrically stimulated ejaculation. The outcomes measured included the average fertilisation and pregnancy rates, embryo quality and the likelihood of having at least one live birth from a single IVF cycle. When comparing the use of fresh or frozen sperm, no difference was found in the pregnancy rate or the number of live births.
The study's lead author, Dr Alan Thornhill, said that the researchers were concerned that frozen sperm might reduce the birth rate, but now, he said 'we believe that concern is unwarranted'. Dr Shane Russell, leader of the research team, told the conference that the 'data supports the continued and expanded use of frozen sperm for IVF'. Dr Thornhill added: 'IVF can be a physically, financially and emotionally draining process for couples, and use of frozen sperm eliminates the pressure of obtaining sperm on a specific day and unnecessary risk to the woman due to ovarian hyperstimulation'.