A statement from Lynn's representative on the singer's website says the 81-year-old started feeling poorly midway through her three-week tour and is taking some time off to be treated.
The statement says Lynn, who just finished a Canadian tour, is rescheduling both Iowa shows.
Last year, the singer postponed two shows to undergo more physical therapy following total knee replacement surgery.
Lynn was born in the coalfields of eastern Kentucky and chronicled her life in an autobiography and song, both titled "Coal Miner's Daughter."
