eggs

Red spots in an unincubated egg do not mean that an egg is fertile. They are usually called blood spots, or meat spots. They occur when a blood vessel ruptures in a hen's oviduct. Blood spots are pretty common in eggs, and do not affect the eating quality of them. Look up some pictures of eggs with blood spots, and see if they look like what you see in your hen's eggs.

There is only one visible difference between a fertile and infertile egg before they are incubated. An infertile egg will have a very small white dot on the egg yolk. The dot will often be indistinct, and will be mostly solid. Fertile eggs, though, will have a small white "bulls eye" on the yolk. Instead of being a solid white circle, it will look like a small white dot with a ring around it. At first, the differences between a fertile and infertile egg will be rather indistinguishable, but with practice you can identify them easily by looking at the yolks.

Here is a link to telling whether an egg is fertile or infertile before it is incubated: https://www.backyardchickens.com/t/16008/how-to-tell-a-fertile-vs-infertile-egg-picturesIt should explain (and show you) the small white spot and "bull's eye".

 

Red spots on the yolk are not a sign of fertility. Instead, these spots (called "blood spots" are a bit of blood that got incorporated into the egg. This usually happens when a blood vessel in the wall of the oviduct ruptures during the formation of the egg, or when a similar thing happens in the wall of the ovary. Blood spots are most common in the eggs of young birds or old birds; every chicken usually produces an egg with a blood spot at least once in its lifetime.

Eggs with blood spots are fine to eat, though they are a bit unappetizing, and don't usually mean that something is wrong with your birds. However, if every egg that you are finding has a blood spot, that is a bit concerning. Chances are that they will grow out of it as they continue producing, though.

A sign of fertility in a non-incubated egg is a bulls-eye (with rings) shaped blastoderm (the white spot on the surface of the yolk). An infertile egg will have a solid white blastoderm. This method is not the most accurate in determining fertility.