In Act 1, Scene 2, Charmian and certain other attendants of Cleopatra converse with the Soothsayer, who foreshadows the death of Cleopatra at the end of the play:
SOOTHSAYER: You shall outlive the lady whom you serve.
CHARMIAN: O, excellent! I love long life better than figs.
SOOTHSAYER: You have seen and proved a fairer former fortune
Than that which is to approach.
CHARMIAN: Then belike my children shall have no
names. Prithee, how many boys and wenches must
Though Charmian writes the Soothsayer off eventually, this passage, early on in the play as it is, primes the reader to expect Antony and Cleopatra's story to end in tragedy, foreshadowing the fall of both. This foreshadowing comes quite early in the play and may be easy for the audience to write off, as Charmian does. These small moments that presage the play's tragic ending eventually grow in intensity and frequency, working to build the sense of dread and contribute to the notion that these characters were doomed from the start.
Despite the fact that the words of soothsayers were highly regarded in pagan societies, Charmain does not seem to take the Soothsayer seriously. This evokes, as much of Antony and Cleopatra does, the historical shift away from mysticism and towards institutionalized Christianity.