In the 18th and 19th centuries, sideshow carnivals known as misemono were a popular form of entertainment for the sophisticated residents of Edo (present-day Tokyo). The sideshows featured a myriad of educational and entertaining attractions designed to evoke a sense of wonder and to satisfy a deep curiosity for the mysteries of life. One popular attraction was the pregnant doll.

Although it is commonly believed that these dolls were created primarily to teach midwives how to deliver babies, evidence suggests they were also used for entertaining purposes. (Link)