Hi, Mark —
Generally, eggs do not contain a baby chicken. They are full of proteins but are unfertilized and are not the product of a union between rooster and hen.
Hens generate eggs whether a rooster is around or not.
Such eggs being unfertilized will never hatch as chicks, however eggs used to be forbidden during Lenten periods of abstinence as well as dairy and other animal products.
The rules have just been relaxed. This may help explain the custom of Easter eggs.