Sometime in Ancient Greece, Leto became one of the illicit lovers of Zeus, and became pregnant with Apollo and Artemis.
When Hera, the Queen of the gods, discovered the pregnancy, she was hurt by her husband's affair and sought revenge on Leto. To stop the her from giving birth, Hera caused both the mainland and all islands to shun Leto while she was in labor. They halted her labor causing her more pain every minute, she eventually sought refuge on the newly formed isle of Delos, which was not yet connected to the ocean floor and didn't fall under Hera's decree. There she gave birth to her twins.
Leto was threatened and assailed in her wanderings by monsters and these became the enemies of Apollo and Artemis when they grew older. One was the Titan Tityos, a phallic being who grew so vast that he split his mother's womb and had to be carried to term by Gaia herself. He attempted to waylay Leto near Delphi, but was stopped.
Another ancient earth creature that had to be overcome was the dragon Python, which lived in a cleft of the mother-rock beneath Delphi and beside the Castalian Spring. Apollo slew it when he was grown and took possesion of the Oracle of Delphi, but had to do penance and be cleansed afterwards.