PORTLAND, Maine — Shiloh Pepin, a girl who was born with fused legs, a rare condition often called “mermaid syndrome,” and gained a wide following on the Internet and national television, has died. She was 10.

Doctors had predicted she would survive only for days after her birth at the most, but the girl, described by her mother as “a tough little thing,” died at Maine Medical Center on Friday afternoon, hospital spokesman John Lamb said. She had been hospitalized in critical condition for nearly a week.

Being born with “mermaid syndrome,” also known as sirenomelia, meant that the Kennebunkport girl had only one partially working kidney, no lower colon or genital organs and legs fused from the waist down. Shiloh’s story was featured recently on “The Oprah Winfrey Show” and other national television programs.

For a while, Leslie Pepin said, things were looking up. “She’s a tough little thing,” she said of her daughter earlier this week.