Katharina Dalton (11 November 1916 – 17 September 2004) was a British physician and pioneer in the research of premenstrual stress syndrome. It is said that she coined the term for the syndrome. On September 17, 2004, Dr. Katharina Dalton died in Britain at age 87.
Katharina Dalton began her career studying at the London Foot Hospital as a podiatrist. After her first husband died in World War II, Dalton decided to switch careers in the medical field, and eventually obtained a medical degree at the Royal Free Hospital. 
Dr. Dalton became involved in the treatment 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, Dr. Dalton, along with Greene, published the theory in British medical journals in 1953—first using the term "premenstrual syndrome," or PMS.
Dr. Dalton, who treated numerous women after setting up her own practice, 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, Dr. 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. Her research showed that during times of severe PMS, students' academic performance dipped and women were more likely to abuse their children or commit crimes. From historic anecdotes, she even concluded that Queen Victoria suffered from PMS, as indicated by reports of her monthly screaming and throwing objects at her husband, Prince Albert.
She is largely credited with developing the use of menstrual charts for the diagnosis of the disorder, and argued that the timing of PMS in women was associated with higher rates of suicide attempts, alcohol abuse and violent crimes. PMS, Dr. Dalton argued, was brought on primarily by deficiencies of progesterone and could be alleviated with hormone therapy. She also believed that the hormone could be used to ease postnatal depression. But today most experts disagree with those findings and instead rely on selective serotonin reuptake inhibitors, or S.S.R.I.'s, and other medications for the treatment of PMS.
In her later works, Dr. Dalton helped demonstrate that depression and other disorders could be aggravated by PMS, particularly around the last few days of the menstrual cycle or the first days of menstruation. Dr. Dalton eventually became the first female president of the general practice section within the British Royal Society of Medicine.
Another observation made by Dr. Dalton was that some symptoms of PMS, such as hypertension, edema, and albumin in the urine, were predictors of toxemia during pregnancy. Patients were administered an initial dose of progesterone during early symptoms, and was given continuous treatment if symptoms were still present. Using progesterone in trials of intervention in maternity hospitals, the incidence rate of toxemia dropped from 9 percent to 1 percent.
Dr. Dalton refused using synthetic progesterone in treatment  as she believed it was the cause of various side effects. She opted for the use of natural progesterone in treatments, which is found in sweet potatoes. In addition, Dalton only supported the use of natural progesterone as she claims that only natural progesterone fit progesterone receptors. Most of her treatments used generous doses of progesterone as she believed that there was no unsafe dose, with 400 mg via suppository being the minimum dose. Other positive effects of progesterone include increased hair growth in women and brain trauma treatment.
Her books include: Once a Month: The Original Premenstrual Syndrome Handbook (1978) which became a best seller, and Depression after Childbirth: How to Recognize, Treat, and Prevent Postnatal Depression.
After the death of her first husband, Katharina Dalton remarried Tom Dalton, who passed away in 1992. She has four children, Michael, Thomas, Wendy, and Maureen. Dalton also has five grandchildren, including the British MEP Daniel Dalton.
- O'conner, Anahad. "Katharina Dalton, Expert on PMS, Dies at 87". New York Times. The New York Times Company. Retrieved 2014-12-11.
- Raymond Greene