Sara Josephine Baker was born in 1873 in Poughkeepsie, New York, to Daniel Mosher Baker and Jenny Harwood Brown.  Josephine was just 16 when her father and brother died in a typhoid fever epidemic.  It was this event that made Josephine decide to give up a scholarship to Vassar College and go to medical school to become a physician.  She enrolled in the Woman’s Medical College of the New York Infirmary and graduated second in a class of 18 in 1898.  Josephine served her internship at the New England Hospital for Women and Children in Boston, Massachusetts.  This experience allowed her to study the effects of poverty, poor sanitation, sickness and infant mortality up close.

Her year in Boston completed, Josephine and her classmate Dr. Florence Laighton moved to New York City where they opened a private practice together.  Income from their practice did not produce sufficient income (just $185 the first year) and Josephine took second jobs as a medical examiner for the New York Life Insurance Company and as a medical inspector for the New York City Department of Health.  As an inspector, Josephine examined sick children in New York City schools and worked on projects to control the spread of infectious diseases.  In one famous case, she helped catch Mary Mallon, also known as Typhoid Mary, a cook who was a known carrier of the disease.

In 1907, Josephine was promoted to assistant to the Commissioner for Public Health in New York City.  Josephine worked on preventive health care programs for young children, which resulted in a significant drop in the rate of infant mortality.  This led to the Department of Health creating a division of child hygiene and naming Josephine as its director in 1908.

Under Josephine’s direction, the division set up a series of “milk stations,” where nurses could examine babies, schedule checkups, and distribute milk.  Older sisters of these babies were enrolled in the “Little Mothers League,” which provided training in infant care so mothers could work.  Midwives were trained and licensed.  The silver nitrate drops given to infants to help prevent blindness now came packed in beeswax containers to help insure their safety and cleanliness.

Josephine invented an infant formula which mixed water, calcium carbonate and lactose with cow’s milk (an innovation that could be mixed in the home).  She also designed baby clothing that was light and could be opened from the front.  The design was bought by McCall’s and the patterns were distributed at no cost by the Metropolitan Life Insurance Company.  During Josephine’s time in office, the infant mortality rate in New York dropped from 1,500 per week to 300.  Josephine also saw to it that each New York City school would have its own doctor and nurse, who would check children for head lice and diseases such as trachoma.  She went against the prevailing thought of the time when she emphasized prevention of disease over treatment.

In 1915, William Park, dean of the New York University Medical School, asked Josephine to lecture on the subject of children’s health.  Josephine had one condition – that she be allowed to enroll in the program and attend classes toward a degree in public health.  At first, Dean Park refused.  Women were not allowed in the Medical School.  However, when he realized that Josephine had no equal in her knowledge of children’s health he knew he had to allow her to attend.  In 1917, Josephine received a doctorate in public health, the first woman to do so at New York University.  Other women soon followed at the University and Josephine spent 15 years teaching there.

Josephine retired in 1923, but kept on working and serving the community.  She was a consultant on child hygiene to a number of organizations, including the New York State Department of Health, the US Department of Labor, and the US Public Health Services.  She served as a member of the Health Committee at the League of Nations.  In addition, she wrote numerous articles on the subject of preventive medicine before her death in 1945.