Katharina Dalton (11 November 1916 – 17 September 2004) was a British physician and pioneer in the research of premenstrual stress syndrome (PMS), coining the term, treating many women and testifying as an expert witness in influential court cases. Background Katharina Dorothea Kuipers was born in London on 11 November 1916 to parents Anna Knoester and Johannes Kuipers. Johannes Kuipers, a merchant and freemason, died when Dalton was young. Despite her family's financial troubles, Dalton attended the Royal Masonic School for Girls in London. As she grew, she wanted to be a doctor and, after winning a scholarship to the London Foot Hospital, first trained to be a chiropodist. Dalton married her first husband, Wilfred Thompson, in 1939, but he died in World War II, not long after their son was born. Dalton then decided to change medical speciality, and obtained a medical degree at the Royal Free Hospital. Before graduating, she married Thomas Dalton, with whom she had three more children. Following the death of her husband Thomas in 1992, Katharina retired shortly after in 2000. She lived the rest of her days in Hereford and Poole, England and ultimately died on 17 September 2004. Accomplishments Dr. Dalton became involved in the study of PMS in 1948, when, as a pregnant 32-year-old medical student, she realized her monthly migraine headaches had disappeared. Consulting with endocrinologist Dr. Raymond Greene, she concluded that the headaches could be attributed to a deficiency in the hormone progesterone, which drops before menstruation but soars during pregnancy. After further clinical study, Dalton and Greene published the theory in British medical journals in 1953 — first using the term "premenstrual syndrome" or PMS. Dalton treated numerous women after setting up her own practice and concluded that PMS was a cyclical hormonal illness occurring in the 14 days following ovulation, with the most severe symptoms evident during the final four days before menstruation. In direct conflict with the views of many of her male colleagues, Dalton said the symptoms were more physical than psychological and included migraine headaches, asthma, epilepsy, skin lesions, irritability, fatigue, and depression. In addition to her patients, she studied teenage schoolgirls, the mothers of abused children and women confined to prison for serious crimes, including murder. For example, she testified as an expert witness at the Old Bailey in the trial of Nicola Owen, who had burnt her parents' house down. Her research