One of the sextuplets was in critical condition Monday and three others were in serious condition.
The five boys and one girl were born Saturday night to Karoline and Ben Byler of Wesley Chapel, more than two months early. The babies all weighed between 2 and 3 pounds (910 grams to 1.4 kilograms) each.
Ryan Patrick was in critical condition, while one brother, Jackson Robert, was upgraded Monday from critical to serious condition, according to All Children's Hospital in St. Petersburg.
Another boy, Charlie Craig, and the girl, MacKenzie Margaret, remained in serious condition, officials said. Two other boys, Brady Christopher and Eli Benjamin, remained in stable condition.
The babies will likely remain in the hospital through November. Doctors said their birth weights were normal for their stage of development.
The Bylers said they used fertility drugs after their 4-year-old daughter asked for a sibling.