First, congratulations on your pregnancy. That's terrific. It is unusual to have so few eggs from large follicles but certainly not impossible. Sometimes eggs that are very close to mature will spontaneously mature in the lab. For eggs a little less mature, it is possible to coax them along in maturation medium but not all programs offer this. There is a downside to maturation in vitro which is that we don't really understand exactly how to mimic the natural maturation process in vitro though this area is an intense research area. The ovary is so marvelously complex and fine tuned- it's hard to duplicate in a culture dish. So the eggs matured in vitro produce a polar body- a sign that they are mature on one level but maybe not fully matured in other areas- for example- maternal imprinting. There is some evidence that long periods of in vitro maturation may cause large offspring syndrome. I wrote about that in my blog if you want to read more about it. So the answer is I don't know why you had so many immature but in the end, as you say, it didn't matter because you are pregnant now. Best Wishes, Carole