Leto is the daughter of the Titans Coeus and Phoebe. She was another of Zeus' conquests and bore him two famous children, Apollo and Artemis. These were born on the sacred island of Delos to escape the wrath of Zeus' angry wife Hera who proclaimed that no country should give her sanctory. The island of Delos was anchored to the bottom of the sea by a helpful Poseidon and thus not a country.
Leto had to go through agonising labour as Hera convinced her daughter Eileithyia (the midwife goddess) not to assist Leto.
Leto is one of the few Titanesses to be worshipped in Greece and one of Apollo's most important temples were later built on the island of Delos.