Dr. Doris L. Wethers, who broke racial barriers in the medical world before gaining renown for research and advocacy that helped lead to mandatory testing of all newborns for sickle cell anemia, died on Jan. 28 in Yonkers. She was 91.

The cause was complications of a stroke, her daughter-in-law Lisa Booker said.

In 1965, Dr. Wethers became the first black chief of a medical department at a New York City voluntary, or private nonprofit, hospital when she was named director of pediatrics at Knickerbocker Hospital in West Harlem.

Knickerbocker, which had a history of refusing to admit black patients, was renamed Arthur C. Logan Memorial Hospital before it closed in 1979.