The baby's 27-year-old mother told police that she had been sleeping in bed with her two children at the Stamford Plaza Hotel in Connecticut.
In the morning, she woke up to find her baby daughter lying on a pillow on the floor.
She said the baby must have fallen off the bed sometime during the night and became lodged in the tight crevice between the bed and wall.
As the mother - who has not been identified by police - picked her baby up, she noticed she wasn't breathing.
"We are exploring all avenues in this tragic situation and will have more after we receive the results of the autopsy"
The 25-year-old father, who was sleeping in another bed, was awoken by his partner's screams, according to police.
Medics and police rushed to the hotel and attempted to revive the baby, before taking her to hospital.
She was pronounced dead a short while later.
The couple's 2-year-old son had also been sleeping in the same bed as the mother, but was unharmed.
Police have, so far, said it is too early to give an exact cause of death, and will be conducting an investigation.
They said: "We are exploring all avenues in this tragic situation and will have more after we receive the results of the autopsy."
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