Age and method of freezing affects the success of egg freezing

Fertility preservation for women involves undergoing the first half of an IVF cycle – with hormones being used to stimulate egg production and eggs being surgically retrieved from the woman’s ovaries. These eggs are then frozen by one of two methods – slow freezing (SF) or rapid freezing through vitrification (VF). In the future when the woman is ready to pursue a pregnancy, she undergoes the second half of the IVF cycle. Her frozen eggs are thawed and fertilized with her partner’s sperm or the sperm of a donor. One or two embryos are then transferred to the woman’s uterus in the hopes of achieving a viable pregnancy.

Research has demonstrated that live birth rates are lower for IVF cycles using frozen, rather than fresh eggs. The results of a study to be published in the journal Fertility and Sterility also suggest the method used to freeze the eggs – SF versus VF – appears to affect the success of IVF.  Researchers from New York Medical College and the University of California Davis conducted a meta-analysis exploring the probability of live birth rates from IVF using intracytoplasmic sperm injection (ICSI) with slow frozen eggs versus eggs rapidly frozen through vitrification. Ten studies conducted from 1996 through 2011 were included in the meta-analysis, which yielded data from 1806 patients undergoing 2265 cycles, using 11,122 eggs that were slow frozen and 1,957 eggs that were vitrified. The researchers analyzed data from patients who underwent IVF using their own eggs, and explored several variables in their analysis (e.g., patient’s age; freezing method; number of eggs frozen, thawed, injected, and transferred).

The results demonstrate that while survival and fertilization rates were higher for vitrified eggs (VF), live birth rates following IVF were higher for cycles using slow frozen eggs (SF). In addition, implantation and live birth rates were found to decrease as the patient’s age increased, irrespective of the method of egg freezing. Eggs frozen by either method before the age of 30 had significantly higher implantation and live birth rates than eggs frozen after the age of 40.

If you are considering freezing your eggs to preserve your fertility, you may want to speak with your doctor about your fertility testing and preservation options.

To read more about fertility preservation, click here, here, and here.

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