When freezing eggs, it is not the total number of eggs retrieved that matters most, it is the number of eggs that are of high quality. Eggs must first respond to the stimulants needed for ovulation, successfully fertilize and begin normal cell division. Ovarian reserve is an indicator of the number of eggs remaining, but even with a good reserve the number of poor quality eggs increases with age.
There is no clear answer to the best age to freeze eggs. Research shows at the age of 28, women begin to notice a decline in fertility. By age 38, fertility takes a more dramatic curve with egg quantity and quality declining exponentially. By the age of 44, even with the help of in vitro fertilization a woman only has a 2% chance of success per attempt with her own eggs.
A woman using either donor eggs or eggs she froze at a younger age has nearly the same chance of pregnancy resulting in a live birth when she reaches the age of 44. This is because the percentage number of chromosomally normal eggs of a younger woman remains constant even when transferred into an older woman. Women with unexplained infertility fail to realize the link it has to abnormal eggs, especially if the woman continues to menstruate regularly. Menstruating regularity may give a false sense of security as the cycles may be producing only low quality or abnormal eggs. Chromosomally abnormal eggs attribute to miscarriages or genetic diseases of advanced maternal age, such as Down’s syndrome. Down’s syndrome carries 1:1000 odds for women in their 20’s, but increases to less than 1:100 for a woman in their 40’s.
Women entering their 40s will have eggs of poor quality. This is reflected even with the help of in vitro fertilization. IVF success rates for women at the age of 25 are around 45% and drop to 35% by their mid-30s. Success rates decline even further to 19% by age 40 and 3% at age 44.
When a women over the age of 40 uses eggs donated by younger women live birth rates stay in the 50% range. This percentage would be consistent with eggs frozen when a woman was younger for her own use later in life.