Issues of the determination of fetal sex have haunted embryologists. Nowadays vestiges of traditional prejudice against the birth of girls are aided by ultrasound scans. The importance of perfect timing of conception and fetal care has been highlighted by sophisticated IVF (In Vitro Fertilisation) technologies and New Age fetal instruction for generations of middle-aged mothers with declining fertility. As the concept of having one fixed gender increasingly wavers, it is fascinating to find that all these preoccupations with sex determination and gender transformation can be found in ancient Indian and Chinese medical treatises. Nevertheless the ulterior motives naturally change from one context to another. In describing and comparing a number of early and medieval Chinese and Indian sources this article distinguishes between the aims and ambitions of gender technologies in Buddhist and medical sources.