I've been reading about assisted reproductive technology, which is the medical term used for various forms of artificial procreation. The ethical violations in this industry are horrific.
They harvest eggs from either the woman who wants a child, or from a donor (a young woman who has passed rigorous medical tests), then they fertilize the eggs in a petri dish. Very often, they create more embryos than are needed at the time, and they freeze those embryos for possible later use.
There was a study done in 2003 to estimate the number of frozen embryos in the U.S.
430 ART clinics were surveyed; 340 replied to the survey.
Those 340 clinics had 391661 frozen embryos on-site. Some clinics store embryos off-site, at a facility owned by them or by another organization. These off-sites were also surveyed and reported 9677 frozen embryos. Since some off-sites could not report which embryos were associated with which clinics, some double counting might have occurred, so the more conservative number of 4865 was used, i.e. only those off-site embryos that could be assigned to a specific clinic. This omits counting some frozen embryos
391661 plus 4865 = 396526 frozen embryos in the 340 clinics that responded to the survey.
Add to this another 51753 frozen embryos estimated by this survey in clinics that did not respond, but for which they had data from 1999. This still leaves 32 clinics for which there was no data. Nearly every reponding clinic was using cryopreservation of embryos, so the total is still an under-estimate
391661 frozen embryos (FE) in clinics
plus 4865 FE in satellite facilities (off-site)
plus 51753 estimated FE in clinics with data from 1999, but not 2003
equals 448,279 frozen embryos in the U.S.
But since the off-site facilities data is under estimated, and since 32 clinics provided no data, the number is more likely above 450,000 FE
Add to this number the additional embryos frozen since 2003, and the number is even higher.
The same study references studies done in the UK (52,000 frozen embryos in 1996) and Australia/New Zealand (71,176 FE in 2000). And those numbers also would almost certainly have increased since that time.
Now the count of FEs is 571,455 and this does not even include many other developed nations using ART.
The authors of this study determined that an estimate can be made of the number of frozen embryos based on the number of 'cycles' of attempted ART (which begin with the stimulation of the ovaries to produce eggs). Multiplying the number of cycles by 0.77 gave an estimate of the frozen embryos.
World Report on ART 2003 estimated total ART activity in the whole of the world is estimated at 1.1 million cycles a year
Cryopreserved Embryos in the United States and Their Availability for Research
Fertil Steril 2003;79:1063-9
ART Report for 2007