Dr. Martha May Eliot worked for the Children's Bureau, a national agency established in 1912 to improve the health and welfare of American children, for over 25 years. First employed as director of the bureau's Division of Child and Maternal Health, Eliot went on to become assistant chief, and then chief, of the whole organization. She was the only woman to sign the founding document of the World Health Organization, and an influential force in children's health programs worldwide.

Martha May Eliot was born in Dorchester, Massachusetts in 1891, to Christopher Rhodes Eliot, a Unitarian minister, and Mary Jackson May. She majored in classical literature at Radcliffe College and completed her premedical training before graduating in 1913. She first applied to Harvard Medical School, which did not admit women at that time, before beginning her medical education at Johns Hopkins University School of Medicine in 1914. She received her M.D. with honors in 1918, the same year as her classmate and life partner, Ethel Collins Dunham.

Eliot and Dunham had hoped to complete their internships at the same institution, but only Dunham was accepted at Hopkins. Eliot instead went to Peter Bent Brigham Hospital, Boston, followed by a residency in pediatrics at St Louis Children's Hospital from 1919 to 1920. She was then invited to become the first chief resident in Edward A. Park's new department of pediatrics at Yale Medical School, working at New Haven Hospital. Dunham was appointed to Yale in 1920. Eliot rose steadily through the ranks of the university, serving first as resident, then instructor, assistant clinical professor, and finally, from 1932 to 1935, associate clinical professor.

With Edwards A. Park, Eliot worked on rickets, a nutritional deficiency that affects bone growth and creates bow legs. In the early 1920s they established the therapeutic importance of vitamin D, cod-liver oil, and sunbathing, and in 1938 they published their authoritative essay on the condition in Joseph Brennemann's Practice of Pediatrics.

In 1924, Eliot was named director of the Children's Bureau's Division of Child and Maternal Health, commuting to Washington for one week a month whilst continuing her duties at New Haven Hospital. A decade later, in 1934, when she was made assistant chief of the Children's Bureau she moved to Washington full-time.

During World War II Eliot was sent to England to study the impact of defense activities on children in Britain, observing the evacuation of city children to stay with families living in the countryside and publishing her report Civil Defense Measures for the Protection of Children in 1942. She was also a leading figure in the war work at home. She ran the Emergency Maternity and Infant Care Program for the wives and children of servicemen, which served the families of 1.5 million American soldiers. In the four years the program ran, from 1941 until the end of the war, Congress gave the program $130 million dollars to train personnel and send them out to struggling hospitals, clinics, and directly into people's homes. Eliot received the Lasker Award for this work in 1948.

After World War II Eliot served on the U.S. delegation to the first ever World Health Assembly, the starting point for the creation of the World Health Organization (WHO). She was the only woman to sign the founding document of the WHO. Eliot visited thirteen European countries while studying child health and nutrition, and in 1949 left the Children's Bureau to serve as assistant director general of the World Health Organization in Geneva. Two years later, she returned to the US and was appointed chief of the Children's Bureau.

Martha May Eliot received numerous honors for her work, including the American Pediatric Society's most prestigious award, the Howland Medal, in 1967. In 1947, she became the first woman to be elected president of the American Public Health Association , and in 1948 she was elected president of the National Conference on Social Welfare. She was the first woman ever awarded the American Public Health Association's Sedgewick Memorial Medal, in 1958.

Eliot left the Children's Bureau in 1956, and in 1957 became chair of the department of child and maternal health at the Harvard School of Public Health. After retiring in 1960 she continued her work for the WHO and UNICEF, reporting on medical education in Asia and Africa. She also taught for the American Public Health Association. In 1964, Eliot's legacy was commemorated by the American Public Health Association when they established the Martha May Eliot Award to recognize achievements in the field of maternal and child health care.