These are macroscopic nodules of perivillous fibrin deposition.  If they occupy only a small percent of the placental volume, they are insignificant.  If they are extensive (more than 20% of the placental volume), they may represent massive perivillous fibrin deposition.  This entity can be associated intrauterine growth restriction or even intrauterine fetal demise, and it may recur.

I invited our placental expert pathologist, Dr. Parks to review above photos and wrote above evaluation

The photo of Dr. Parks