The couple, who announced their engagement in June, have denied rumours that Cyrus is already pregnant and planning to marry because of it.
However, it has since been claimed that Cyrus and Hemsworth feel ready to have children and would like to do so as soon as possible.
"Miley and Liam really want to have a baby quickly," a source told US Weekly. "They are both mature and ready for this. Miley is 19 going on 40."
Last month, Hemsworth accidentally said that he was already married to Cyrus while speaking to reporters at the Australians In Film Awards.
Cyrus recently blasted paparazzi as "shady and scary" for camping out in front of her house while her brother is in hospital.