Helen and I used in vitro fertilization (IVF) to conceive our son. We did not, alas, have enough extra embryos after implantation to freeze any for later use. (We did, however, use a tried and true frozen sperm “pop-sicle.”) I was still interested, however, in a new study from Copenhagen University Hospital, which reports the counterintuitive result that for IVF, frozen embryos were better than fresh. Babies conceived using previously frozen embryos were of normal birth weight, whereas those conceived through conventional IVF were on average 200 grams lighter.
The lead scientist is not sure why, but says it may be a matter of selection, with only the strongest embryos able to survive the freezing and thawing process. Women who freeze embryos for later use also tended to be younger and healthier, and were less likely to implant the embryos right after the hormone treatments to harvest the eggs, which might have some impact. (This would, of course, be irrelevant for lesbian couples who did what Helen and I did, with the eggs being harvested from one woman and implanted into the other.)
I am not, of course, recommending that you put your blastocysts on ice. This is only one study, and there are many, many variables for any given person’s case. I find the whole science of assisted reproduction pretty fascinating, however, and wonder what options will be available to our children when they are grown.