Thomas Morgan Rotch was born in Philadelphia, the son of Rodman and Helen (Morgan) Rotch. His father came of a New Bedford family, being a great-grandson of William Rotch. His mother was a collateral descendant of John Morgan, the founder of the University of Pennsylvania medical school.
Rotch was graduated by Harvard College in 1870 and by the Harvard Medical School in 1874.
During the last year of his medical course Rotch served, as was customary at the time, as house officer at the Massachusetts General Hospital. His internship was followed by two years of study abroad, particularly in Berlin, Vienna, and Heidelberg; he returned to Boston in 1876, a well-educated physician.
Rotch began at once the practice of pediatrics, a "specialty" unknown before his time; no other physician in the United States had yet attempted to limit his practice to patients in the first two years of life. Entering boldly into a field where the death rate was highest, he established in 1881 and became medical director of the West-End Nursery and Infants' Hospital, the first hospital in the United States to admit only patients within so restricted an age limit.
As early as 1878 he began teaching pediatrics at the Harvard Medical School. The faculty of that institution were soon impressed by the value of his studies and in 1888 a chair of Diseases of Children was founded with Rotch as the incumbent.
He was made a full professor in 1893; his title was changed to professor of pediatrics ten years later, and he held the latter position until his death. In 1896 he published his first book, Pediatrics: the Hygiene and Medical Treatment of Children.
Rotch realized, early in his career, that the high death rate of infants was largely due to bad nutrition. He soon devised a "percentage" method of artificial feeding (Archives of Pediatrics, August 1887) based on a careful estimation of the caloric value of milk. Varying the formula of cow's milk to meet the requirements of the infant and compounding a product free from impurities, he placed the feeding of infants upon a scientific basis. In 1910 he published Living Anatomy and Pathology: the Diagnosis of Diseases in Early Life by the Roentgen Method.
He was a member of many medical associations, and served as president of the American Pediatrics Society in 1891. His work was recognized abroad and in 1902 he addressed the British Medical Association on American methods in the modification of milk for infants (British Medical Journal, Sept. 6, 1902). His paper led to the establishment of a milk laboratory in London, and in 1903 Rotch was appointed consulting physician to an infants' hospital in that city.
Rotch's book "Pediatrics: the Hygiene and Medical Treatment of Children" was one of the first to be written on that branch of medicine. He created the scientific method to improve the value of the milk for infants. He used the Rentgen ray as a means of studying the bone development of growing children. On April 18, 1903, in consideration of the gift of a fund raised by the Rotch's friends to provide a new building, the name of the West-End Nursery and Infants' Hospital was changed to Thomas Morgan Rotch, Jr. , Memorial Hospital for Infants (to the memory of Rotch's son). The new building, erected on the grounds of the Harvard Medical School, was completed in the year of Rotch's death.
On June 4, 1874, Rotch married Helen, daughter of his uncle, William J. Rotch of New Bedford. Rotch's only child, a son, died in 1902, shortly after graduating from Harvard College.
