IVF's Magic Number

According to a new study published in the medical journal Human Reproduction, there is a magic number of eggs for successful in-vitro fertilization: 15. Analyzing more than 400,000 IVF cycles in the U.K., the study found that:

There was a strong association between the number of eggs and LBR (live birth rate); LBR rose with an increasing number of eggs up to 15, plateaued between 15 and 20 eggs and steadily declined beyond 20 eggs. … The results showed a non-linear relationship between the number of eggs and LBR following IVF treatment. The number of eggs to maximize the LBR is 15.

Arri Coomarasamy, one of the study’s authors, says this is one of the first studies to look at the correlation between number of eggs and live births — and not, i.e., simply a successful fertilization.

andy weintraub

Sounds like the "law of diminishing returns" to me; or, more correctly, "the law of variable proportions".
Just goes to demonstrate the very wide applicability of some aspects of economic theory.


The summary above is quite confusing. I've had a very quick look at the paper in question.

When attempting IVF, the first step is to give the woman drugs to induce her to release many more eggs than normal in an ovulation cycle. These eggs are then collected to use for IVF. The number of eggs collected in one ovulation cycle is the "number of eggs" to which the summary refers.

Not obvious from a 2 minute scan of the paper is whether the number of eggs is controllable, and if so, whether controlling it to hit the magic number of 15 would improve outcomes. E.g. there may be an underlying factor which both causes egg number to be low, and also egg viability to be low. Giving more hormones to increase the egg number in such a case would not improve egg viability.

(Disclaimer - I have no background in IVF.)


A personal tale - my wife and I had 16 eggs - 13 that fertilized and 5 that were viable embryos. We were told all of our numbers were good to great for all three numbers. I am guessing that larger number of eggs do not mean more live births because most people probably would never use more than 4 to 6 embryos so more than that does not increase live birth. We were pregnant with triplets but lost them at 21 weeks - we are going to try again but I can tell you the emotional and financial costs would not warrant more than a couple of tries so more good embryos from more eggs may not mean more births for that reason.