How many frozen eggs does it take to make a baby?
Increasingly women are freezing their eggs. Are they freezing enough?
Last Friday, the American Society for Reproductive Medicine released data about the use of assisted reproductive technology in the US for the year 2017. The most significant trend they noticed was an increase in egg freezing.
There were 10,936 cycles of egg freezing for fertility preservation, up from 8825 in 2016 — and way up from 475 in 2009.
This is probably a good time to take a hard look at some other numbers: how many frozen eggs you actually need to have a good shot at live birth. Below, in brief, some findings.
Number of eggs a woman has to freeze to have a good shot at one live birth:
Cobo et al, 2015, Cobo et al, 2016, Doyle et al, 2016
Older women will likely need more eggs to achieve a live birth. The Doyle study, on page 465, shows four predictive graphs according to age. For a 75 per cent chance of live birth, a woman aged 30-34 probably needs 16 eggs; a woman aged 35-37 needs about 19; a woman aged over 38-40 needs 30; the graph for women aged 41-42 doesn't get to a 75 per cent chance.
Average age of women who freeze their eggs:
Cobo et al, 2016 and Hammarberg et al, 2017
Most research on success rates of egg freezing have been done on women younger than the ones who actually do it.
Average number of eggs actually frozen per woman:
Hammarberg et al, 2017
The study had responses from 95 women. Two had tried to store their eggs, but were unsuccessful. Almost a quarter of them had stored fewer than 8 eggs. A third had between 8 and 15 eggs. Another quarter had 16-23 eggs. Only 14 per cent had more than 23. Point being, some women may not be freezing enough eggs to reasonably expect a live birth.
Cobo et al, 2015: "Six years' experience in ovum donation using vitrified oocytes: report of cumulative outcomes, impact of storage time, and development of a predictive model for oocyte survival rate," Fertility and Sterility.
Doyle et al, 2016. "Successful elective and medically indicated oocyte vitrification and warming for autologous in vitro fertilization, with predicted birth probabilities for fertility preservation according to number of cryopreserved oocytes and age at retrieval," Fertility and Sterility.
Cobo et al, 2016. "Oocyte vitrification as an efficient option for elective fertility preservation," Fertility and Sterility.
Hammarberg et al, 2017. "Reproductive experiences of women who cryopreserved oocytes for non-medical reasons," Human Reproduction.
HeyReprotech: Why do so few women go back for their eggs?
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