Yes! I used to get blood spots continually and then my big blue orpington was taken by a hawk. I have not had a blood spot or meat spot since. I miss her, but it is nice to not have to crack into a bowl or candle before giving eggs away.I have YET to have an egg with a blood spot make it to hatch. They start developing but haven't ever gone all the way. There are lots of avid hatcher's on here that set double yolks and do all sorts of "crazy" things.. I would LOVE to see someone have a different experience than mine, so try and tag me if you come across or have it yourself please.
I presume its essentially an impurity that impedes the DNA coding.. like maybe a deformity or cancer. The embryo's don't *appear* to be able to just "absorb" it and continue.
I used to crack every egg in a bowl first.. but have hardly dealt with that, if at all since selling off my Marans stock. They were GOOD, hardy, birds.. good demeanor, dressed well for the table.. it was a VERY tough call to let them go! Other adventures were calling.
Since you know which gal it is, hopefully it will improve. All birds (and situations) are individuals, of that I have NO doubt! How old is she?
Also my research says it *can* be diet related.. I'm a treat miser, feed Purina flock raiser with oyster shell on the side and almost an acre of very decent (lush green with lots of bug and plant diversity) pasture in the PNW.. just for informational/comparative purpose in case the details matter for YOUR research purposes.