Egg Freezing Success Rates
Southern California Reproductive Center (SCRC)
What factors affect egg freezing success rates? When you start looking at the numbers, the first step is to make sure you know which success metric you’re looking at. Successful thawing rates, fertilization rates, pregnancy rates, and live birth rates are all very different things. All of these data points are useful, but it’s important to compare apples with apples. Since the main goal of egg freezing is to hopefully come home with a healthy baby when it’s time to start your family, we’ll look at live birth rates. Even restricting the definition to live birth rates varies on how that number is calculated. The numbers you see published can have a huge range, anywhere from 2% to 40% or more. This is usually because they are measuring different things. The commonly seen 2% to 12% success rate often used to discredit egg freezing is per egg retrieved, using the older freezing methods. Using new, advanced vitrification freezing methods gives numbers more like 4% to 14% per egg retrieved. When you multiply those percentages by the number of eggs frozen, the picture starts to look a lot rosier. There are also many other variables which can make a huge difference in the live-birth success rates: Age at time of egg freezing and number of eggs frozen As with most things fertility-related, age is at the top of the list. In short, the younger a woman is when she freezes her eggs, the higher the likelihood that using those eggs will result in pregnancy and live birth. This is because egg quality drops as women age, and young women in their 20s are more likely to produce a larger number of higher quality eggs in a given egg freezing cycle. That means that when it’s time to use the eggs, there are more chances for success. No matter where a woman is in her reproductive years, the number of eggs she chooses to freeze clearly affects the final chances of pregnancy, by virtue of simple math: more eggs = more opportunities, and the chance for doctors to choose the highest quality, strongest embryos to transfer.