A vasectomy is a surgery that works to inhibit reproduction by interrupting the passage of sperm through the vas deferens, a tube in the male reproductive system. The procedure is a method of inhibiting an individual’s ability to cause pregnancy through sexual intercourse without altering the other functions of the penis and testes. In the US, into the early 1900s, proponents of eugenics, the belief that human populations can be made better by selecting for so-called desirable traits, used the procedure to forcibly sterilize people whom they deemed undesirable. Despite its early associations with eugenics, physicians’ use of vasectomy eventually transitioned into an option for elective contraception. Even with the various shifts in motivation for performing vasectomies, as of 2023, patients have the choice to undergo a sterilization procedure if they want to restrict their own ability to have children.

Lewis Madison Terman was a researcher and university professor who studied educational psychology and advocated for eugenics in the United States during the early twentieth century. The US eugenics movement, which Terman supported, was a collection of scientific research and social programs that aimed to improve human populations through control over human reproduction. One area many eugenicists studied was human intelligence as a means of determining how “desirable” a person may be. During the 1910s, while working at Stanford University in Palo Alto, California, Terman helped devise the Stanford-Binet scale for intelligence testing. As of 2024, the Stanford-Binet test is one of the main methods for providing individual intelligence quotient, or IQ, scores. In addition to the Stanford-Binet scale, Terman promoted the idea that individuals had fixed and inherited capacities for intelligence. Through both his development of a widely used method for measuring human intelligence and his promotion of the idea of intelligence as hereditary, Terman supported widespread social efforts to control human reproduction in the US during the twentieth century.