In 'Rumpelstiltskin', what does the queen promise in exchange for spinning straw into gold?

In “Rumpelstiltskin,” the queen promises her firstborn child in exchange for having straw spun into gold. She is still the miller’s daughter when the bargain is made, but becomes queen after the king marries her. The strange little man helps her meet the king’s impossible demand, and she agrees to pay him with her first child because she has nothing else left.

The bargain develops over three nights. On the first night, the imp accepts a necklace; on the second, he takes a ring. On the third, the room is larger and the miller’s daughter has no possession remaining, so he demands her future child. The king then keeps his promise and marries her.

After the baby is born, Rumpelstiltskin returns to collect the payment. He finally offers to surrender his claim if the queen can guess his name within three days. She succeeds after learning it from a song he sings in the forest. The tale’s 1812 ending is relatively restrained; later Grimm editions gave the imp a much more violent fate.