Betances wrote two books and various medical treatises while living in France. His doctoral thesis, ""Des Causes de l'ávortement"" (The Causes for Miscarriage) examines various possible causes for the spontaneous death of a fetus and/or its mother, was later used as a textbook on gynecology at some European universities. According to at least one medical practitioner who examined it in 1988, his attempt to explain the theory behind spontaneous contractions leading to childbirth were not very different from modern-day theories on the matter.