Chickens do not have a set age at which they stop laying eggs, but they lay fewer eggs as they age. Their peak laying period is at 3 to 4 years of age. Older hens tend to lay fewer eggs in one batch and have longer intervals between egg-laying periods.
A mature hen typically lays an egg every one or two days, depending on its breed. Though it varies with individual birds, most hens start laying eggs when they are six months old. The first eggs are likely to be misshapen and have traces of blood on the shell. Fertilized eggs hatch 21 days after incubation.