Why do my eggs have blood spots in them?
Steve Coe, Ringwood
Laurence Beeken says: The most common cause of blood spots is a ruptured blood capillary in the oviduct as the egg passes through (providing you do not have a cockerel running with the hens, so you can discount a fertile egg which has started to develop), and is more common in some specific lines of birds as it may be inherited. Hybrids tend to suffer form this less often as the tendency has been more or less bred out of the better commercial birds.
Eggs taste no different and it is purely a cosmetic problem.
An increase in blood spots in all of your birds could be indicative of disease, so if you suspect this, get your vet to check your birds out.