Do Kids Take Years Off Your Life? Giving Birth May Make Cells 'Older'

Telomeres naturally shorten as people age, but the structures don't shorten at the same rate in every person. The longer a person's telomeres are, the more times their cells could hypothetically still divide, research has shown. Thus, telomeres are considered a marker of biological age — that is, the age of a person's cells, rather than the individual's chronological age.