Marie-Louise Lachapelle (1 January 1769 – 4 October 1821) was a French midwife, head of obstetrics at the Hôtel-Dieu, the oldest hospital in Paris. She published textbooks about women’s bodies, gynecology, and obstetrics. She argued against forceps deliveries and wrote Pratique des accouchements, long a standard obstetric text, which promoted natural deliveries. Lachapelle is generally regarded as the mother of modern obstetrics.
Lachapelle was born in Paris to Marie Jonet, a competent midwife, and Louis Dugès, a health official, on 1 January 1769. She was the granddaughter and daughter of midwives. She was an only child. Her mother taught her midwifery, which she had learned from her mother, and she quickly became skilled. When she was 15, she performed her first delivery, in which there were complications, though both mother and baby survived thanks to Lachapelle's ministrations. Eight years later, in 1792, she married a surgeon who worked at the Hôpital Saint-Louis. Between 1792 and 1795, she gave birth to a daughter, and stopped working.  After her husband's death three years after their marriage, she had to support herself and her daughter; so she worked again as a midwife. Her daughter then broke away from family tradition and became a nun. Lachapelle died of stomach cancer on 4 October 1821 after a short illness.
While her mother was still alive, she had reorganized the maternity ward, and Lachapelle assisted her as associate chief midwife. By the age of twelve, she was performing complicated deliveries, and at fifteen, she was able to perform single-handedly a version that was potentially fatal if handled incorrectly. In 1797, after her mother's death, Lachapelle inherited her mother's position as head of Hôtel-Dieu, the largest public hospital in Paris. The hospital served the poor and was supported by Notre Dame de Paris. It was the premier obstetric hospital of its time and was renowned for its school of midwifery. She spent part of 1796 and 1797 studying obstetrics under Franz Naegele, She was teaching beside professor Jean-Louis Baudelocque at the Hôtel-Dieu.
Baudelocque realized the need for a systematically organized school for midwives. Because of Lachapelle's medical experience and reputation, she was asked by Minister of the Interior Chaptal to direct the new normal school of midwifery and children's hospital La Maternité which the Napoleonic government established at Port Royal. In order to be a part of the reforms, Lachapelle went to Heidelberg to study, and then returned to Paris, where she became head of the maternity and children's hospital at a newly built teaching hospital, Hospice de la Maternité, an offshoot of the Hôtel-Dieu at Port Royal.
Lachapelle died of stomach cancer on 4 October 1821 after a short illness, her book yet unfinished. The book was finished by her nephew Antoine Louis Dugès, also an obstetrician, who published it in 1825 under the title Pratique des accouchements; ou mémoires et observations choisies, sur les points les plus importants de l'art ("The practice of deliveries; or chosen observations and memories on the most important points of the art"); the book was influential throughout the 19th century. In it, she opposed the use of forceps in childbirth for most cases and advocated for minimal intervention by doctors during delivery.
Jean-Louis Baudelocque and Lachapelle worked well together and developed a course of study for training midwives. After a year-long course, the students took a rigorous examination, and they would receive a diploma from the Ecole de Medicine if they passed. She taught students of midwifery modern techniques for performing a delivery, by demonstrating potential complications with a model and autopsying women who died in childbirth. One of her students was the accomplished midwife Marie Boivin. She treated her students like members of her own family, supporting them physically and spiritually. She moved through the wards, going wherever she was most needed, encouraging patients and patiently teaching staff members. In her teaching, she stressed the importance of noninterference with the birth process unless it was absolutely essential and she opposed the use of forceps except in case of absolute necessity.
Lachapelle is credited with several worthwhile innovations in patient care and midwives' training. It is known that she tried to exclude the hordes of observers from the delivery room, that she advised immediate repair of a torn perineum, that in cases of placenta praevia she quickly dilated the mouth of the uterus with tampons and extracted the infant by turning it, thus saving two lives. She also invented a method of deftly turning a face or oblique presentation so that the infant could be born with forceps, and of replacing a protruding arm or shoulder before it was too late.
Her work in birthing technique, hygiene, and education at La Maternité comprised the majority of her career, where she worked alongside her friend Dr. Jean-Louis Baudelocque, who was in charge of the theoretical part. Lachapelle also made strides in the hygiene practices of the hospital; her efforts to reduce child mortality rates were quite successful, including her restrictions on visitors. Throughout her career, she delivered approximately 40,000 babies; this experience led her to begin writing a textbook on midwifery and obstetrics. Her greatest innovation lay in realizing the value of collecting statistics on great numbers of cases. She also published five case histories in 1819, in the Annuaire Médico-Chirurgical, Observations sur divers cas d'accouchements (rupture du vagin; présentation de la face; issue prématurée du cordon; accouchement précédé de convulsions ("Observations on various delivery cases"). In her three-volume treatise introduced an improved classification of fetal positions, reducing Baudelocque's 94 positions to 22. She always insisted on minimum use of instruments. Her tables settled many questions still debated in obstetrics up to her time: average length of pregnancy, average duration of labor; frequency of certain pelvic abnormalities, etc.
- Lachapelle, Marie-Louise (1821). Pratique des accouchemens ou Mémoires et observations choisies, sur les points les plus importans de l'art (in French). Paris: J.B. Baillière. (volume 1, volume 2, volume 3; Retrieved 6 February 2013.)
She also wrote articles recording her observations for the periodical Annuaire Medico-Chirurgical and furnished statistics for the members of the conseil d'administration des hospices.
- Doctor of medicine degree from a German university 
- Reputation as the preeminent midwife of the First Empire
- Interviewed several times by the most influential persons at court regarding the production of an heir to the throne
- Epstein, Vivian Sheldon (1995). History of Women in Science for Young People. V S E Publisher. p. 35. ISBN 978-0960100279.
- Delacoux 1833, p. 97.
- Ogilvie, Marilyn Bailey (2000). The Biographical Dictionary of Women in Science: L-Z. Taylor & Francis. p. 731.
- Mahul says 11 and a half.
- Oakes 2002, p. 208.
- Mahul, A., Annuaire nécrologique ou complément annuel et continuation de toutes les biographies ou dictionnaires historiques, vol. 2 , Paris, Ponthieu, 1822, p. 229
- Burton, June (2007). Napoleon and the Woman Question: Discourses of the Other Sex in French Education, Medicine, and Medical Law 1799-1815. Texas Tech University Press. p. 98.
- Alic 1999, pp. 306–307.
- June K. Burton casts that into doubt: Napoleon and the woman question: Discourses of the other sex in French education, medicine, and medical law 1799-1815, p. 101
- Stanley, Autumn (1995). Mothers and Daughters of Invention: Notes for a Revised History of Technology. Rutgers University Press. p. 234.
- Ogilvie & Harvey 2000, p. 731.
- Alic, Margaret (1999), Proffitt, Pamela, ed., "Marie-Louise (Dugès) Lachapelle", Notable Women Scientists, Gale Group, ISBN 0-7876-3900-1
- Oakes, Elizabeth H. (2002), International Encyclopedia of Women Scientists, Facts On File, ISBN 0-8160-4381-7
- Ogilvie, Marilyn; Harvey, Joy (2000), The Biographical Dictionary of Women in Science, ISBN 0-415-92040-X
- Annuaire médico-chirurgical des hopitaux et hospices civils de Paris, Paris: Crochard, 1819, retrieved 6 February 2013
- Delacoux, Aloïs (1833), "Lachapelle (Marie-Louise Dugès, veuve)", Biographies des sages-femmes célèbres anciennes, modernes et contemporaines (in French), Paris: Trinquart, pp. 97–106, retrieved 7 February 2013