A new study from the Mayo Clinic shows that couples using in vitro fertilization have the same chance of successful pregnancy whether the sperm used is frozen or fresh. The results were presented at the annual meeting of the American Urological Association. "Without these data, we were concerned that frozen sperm might reduce the birth rate," says Alan Thornhill from the Mayo Clinic, senior author of the study. "Now, we believe that concern is unwarranted."
IVF starts with a woman taking fertility drugs to stimulate her ovaries to produce more eggs than usual. When the eggs are mature, they are retrieved from the ovary and introduced to washed sperm to allow fertilization. The availability of sperm on the day eggs are retrieved is critical to success.
Two to five days after retrieval, the fertilized eggs are transferred to the uterus. Researchers compared the effectiveness of fresh versus frozen sperm by calculating the cumulative live birth rate - that is at least one baby born from a single egg retrieval from the mother. Embryos from a single egg retrieval may be transferred over one or more transfer cycles. For cycles using fresh sperm, the cumulative live birth rate was 51.6 percent. For frozen, it was 53.1 percent.
Dr. Thornhill says Mayo Clinic doctors still prefer to use fresh sperm when possible because the number of sperm and their movement are reduced by freezing and thawing.
If fresh sperm is not available couples can choose to use frozen sperm knowing they aren't reducing their chance for a successful pregnancy.
"The in vitro process is long and can be difficult - emotionally, physically and financially," says Dr. Thornhill. "These results make the process just a little bit easier."
