Maria Delivoria-Papadopoulos, 90, of Lansdowne, an internationally known scientist in the field of neonatal medicine who helped save thousands of infants through her groundbreaking research, died Friday, Sept. 11, of endometrial cancer at the Hospital of the University of Pennsylvania.

During a 50-year career, Dr. Delivoria-Papadopoulos was a professor of pediatrics, physiology, and obstetrics/gynecology at Drexel University College of Medicine, and director of neonatal intensive care at St. Christopher’s Hospital for Children. Both are in Philadelphia.

She was regarded as the “mother of neonatology” and “a legend in the field," Greece’s Neonatal Society said in an online tribute.

“She remains alive in the hearts and memories of the hundreds of doctors she trained and inspired to have a love for sick children, of the hundreds of Greek doctors she opened the way for, and of the thousands of Greek patients who found treatment at specialized centers with her help,” the society said on Sept. 14.

Born in Athens, she was the daughter of Constantine and Kalliopi Delivoria. She earned a medical degree from Athens University.

She came to the United States in 1957 to pursue postdoctoral study in physiology at the University of Pennsylvania. She joined the faculty and created the neonatal unit at Penn, which she ran before leaving as professor emeritus in 2000.

She was on the Drexel faculty from 2000 to 2006, when she was given the Ralph Brenner Endowed Chair in Pediatrics at St. Christopher’s Hospital.

She was honored globally for her achievements and continued research in neonatal medicine throughout her life. Her most important contribution was taking the iron lung used to treat polio victims in the 1950s and adapting it to support the breathing of premature babies. Another was the use of magnetic resonance imaging to assess the infants' brains.

She was the first doctor to place an infant on a respirator to help with respiratory distress syndrome, her family said in a statement. She was also the first woman and doctor to demonstrate the effective use of mechanical ventilation to treat lung disease in premature infants, the family said.

“Her nearly 60-year medical career was dedicated to at-risk newborns, and she touched the lives of countless children,” St. Christopher’s Hospital said in an online post last weekend.

One infant on whose condition she consulted in 1963 was Patrick Bouvier Kennedy, the son of President John F. Kennedy and first lady Jacqueline Kennedy.

Dr. Delivoria-Papadopoulos was called when the baby developed breathing problems. She didn’t treat the child, though, because she was working at the Hospital for Sick Children in Toronto. It was considered unseemly for a Canadian physician to treat the child of a U.S president.

The child was treated by a Boston specialist who placed him in a hyperbaric chamber filled with 100% oxygen, similar to the ones used by divers. Despite frantic efforts by doctors, the child lived for only 39 hours, dying at 4:04 a.m. Aug. 9.

Because of her expertise, she served as an adviser to the National Institutes of Health. She was the author of 400 scientific publications.

Dr. Delivoria-Papadopoulos had an extensive network of scientific proteges as well as thousands of surviving patients, including many for whom she was the only hope. “They kept in touch with her always,” said her son James C. Patterson.

Despite her elevated status in medicine, she lived simply.

“Her life would have been viewed as a blue-collar sort of status,” said Joseph McGowan, a family friend for 40 years. “She spent a month in Greece every summer, providing free medical care to Greek children.” She worked from a tent and gave each child a toy so they wouldn’t fear doctors.

After her mother died in 1985, Dr. Delivoria-Papadopoulos wore black, sometimes punctuated with a signature white blouse, for the rest of her life.

Her husband, Christos Papadopoulos, died in 2002. Besides her son James, she is survived by another son, Constantine C. Patterson, and a grandson.

Services were private. Memorial donations may be made to any veterans organization.