Leila Denmark, the world's fourth-oldest person at 114, was the longest-practising medical practitioner in the world, only hanging up her stethoscope at the grand old age of 103, by which time she had helped invent a cure for whooping cough and broken down gender and racial barriers in America.
Born Leila Alice Daughtry in the southern state of Georgia in 1898, her family was of Irish descent -- her surname is an augmented spelling of Doherty.
She grew up on a small farm in the town of Portal, Bulloch County, Georgia, about 170 miles south-east of Atlanta. The third of 12 children to Elerbee and Alice Cornelia Hendricks Daughtry, she grew up in a farming community. From a young age she had a passion to heal, tending to plants and wanting to heal animals.
Denmark earned a BA degree from Georgia's Tift College in 1922 and then taught science. However, realising that her ambitions lay in medicine, she pushed aside the prejudices in the South and enrolled at the Medical College of Georgia in Augusta in 1924.
Four years later and the only woman in a class of 52 students, she became the third woman to earn a medical degree from the college.
Three days after graduation, she married her long-term sweetheart, the banker John Eustace Denmark. The couple moved to Atlanta, where she began her internship in the segregated black wards of Grady Hospital.
That same year, Denmark became the first resident physician and admitted the first sick baby at the newly founded Henrietta Egleston Hospital for Children (now Children's Healthcare of Atlanta) when it opened.
In 1930 she began a second internship at Children's Hospital of Philadelphia, before returning home to give birth to her only daughter, Mary Alice.
The following year Denmark established her private practice in paediatrics in her Atlanta home.
Her emphasis was on good parenting, good nutrition and common sense. She also gave time each week to the Central Presbyterian Church, which opened a charity baby clinic. Throughout her career, her office was always in or near her home and open all hours for those in need of care.
When whooping cough swept through Atlanta in 1932, Denmark conducted pioneering research in the diagnosis, treatment and immunisation of the disease that killed so many babies. Working with Eli Lilly and researchers at Emory University, Denmark's findings led to the development of the pertussis vaccine and the modern-day DPT vaccination.
During her 70 years as a paediatrician, Denmark preached preventive medicine. At the mid-point of her career, from ideas formulated over the previous four decades, a book outlining tips for raising healthy children was published in 1971, Every Child Should Have a Chance.
Unmoved by generations of baby experts advocating "hands-off" parenting, her book extolled a child-rearing philosophy that placed responsibility for a child's health and happiness solely on parents.
She later explained: "If we had every mother taking care of their children, we wouldn't need prisons."
Denmark also believed strongly that a woman should not leave home to join the workforce. She suggested that children placed in day care would grow to have little self-discipline or confidence in others.
To keep costs to a minimum in a country that had no free healthcare service, Denmark did not employ a nurse or receptionist and relied on a "sign-in sheet" to bring order to her waiting room. She also rarely charged patients more than $10 for an office consultation.
Over the years, her Alpharetta farmhouse office was visited by families from all walks of life. Her medical instruments were few and barely changed: a stethoscope, an otoscope, blood pressure cuff, chemicals to test urine and to measure haemoglobin, and, most of all, her inquiring mind.
Denmark gained a reputation for being able to diagnose a child's illness from just looking -- and as a no-nonsense doctor. In an interview, she recalled: "When a mother asks, 'Doctor, what makes my baby so bad?'", she was likely to get the answer: "Go look in the mirror. You get apples off apple trees."
Denmark received many honours and awards, including the Fisher Award (1935); honorary doctorates from Tift College (1972); Mercer University (1991); and Emory University (2000). She was Atlanta's Woman of the Year in 1953 and won the Atlanta Business Chronicle's lifetime achievement award in 1998. In 2002, the Georgia General Assembly commended Denmark "for her stellar medical career".
As she approached her 110th birthday, Denmark credited her longevity to drinking only water, eating no refined sugars and including a protein and vegetable with every meal. She added: "You keep on doing what you do best, as long as you can. I enjoyed every minute of it for more than 70 years."
Leila Denmark's husband predeceased her in 1990. She is survived by her daughter.
Leila Daughtry, doctor and author: born in Portal, Georgia, February 1, 1898; married John Eustace Denmark 1928 (died 1990; one daughter); died in Athens, Georgia, April 1, 2012.