Miriam Stern was born in Newcastle upon Tyne. Her father Sidney was a nurse and her mother Jenny worked for the Newcastle school dinners service. Her sister is social justice activist Murreil Hazel Stern. Her family was Orthodox Jewish. Her father was born Jewish and her mother converted to Judaism.
Stern grew up on a council housing estate. Her mother was a dressmaker who taught Miriam how to make her own clothing, and from an early age she bought remnants of cloth with her pocket-money. Up until her teens, she fashioned her own designs, complemented with cheap and improvised accessories.
As a teenager she attended school on a scholarship and was shy. Inspired by her father, she had early aspirations to become a doctor. Outside of studies she enjoyed music, danced and played table tennis. Stern attended the Central High School in Eskdale Terrace and trained as a nurse at the Newcastle General Hospital (Royal Free Medical School). She went on to study medicine at King's College, Durham (which became Newcastle University in 1963).
After qualifying as a doctor, Stoppard worked at the Newcastle's Royal Victoria Infirmary and specialised in dermatology as a senior registrar at Bristol Royal Infirmary. She became a research director and then managing director in the pharmaceutical industry for Syntex. She became well known during the 1970s and 1980s as a television presenter on scientific and medical programmes such as Don't Ask Me and Where There's Life.
Stoppard has written several books about health, including the Children's Medical Handbook, but particularly on the subject of women's health. She writes on health issues and acts as an agony aunt for the Daily Mirror, having previously answered readers' letters for The TV Times magazine. Her company, Miriam Stoppard Lifetime, sells her books and health products.
In August 2012, writing in the Daily Mirror, Stoppard supported UCL's Institute of Child Health research which suggested reviewing the recommendation of exclusive breastfeeding until six months, adding that the appearance of teeth should signal the end of breastfeeding. She was named Journalist of the Year at the Stonewall Awards on 6 November of that year.