(This paper is part of the accepted workshop "Christianity and Medicine, Health, and Disability: Virginity's Anatomy.")
Patristic authors take up a biblical expression about God or offspring "opening the womb" to refer not only to conception and birth, but also to female defloration by a man. Surprisingly, in the ancient Mediterranean world, "virginity" did not necessarily denote a state of a woman's intact hymen. In writings of late antiquity, however, assumptions about the term "virginity" shift; it is increasingly understood as an anatomical state, verifiable by medical examination and dependent upon the integrity of the hymen. Patristic discussion of Mary's virginity in partu provides one significant example of how this shift in meaning impacted Church teaching. Exegesis of a biblical phrase thus serves as a useful index for changing definitions of female virginity, revealing an intensified focus in late antiquity on the female body that masks an earlier definitional fluidity. The fertility-focused use of the phrase found in Irenaeus, Origen, and some fourth-century writers such as Ephrem gives way to a use of the phrase that references male destruction of female virginity--a meaning anticipated by Tertullian, developed by Ambrose, and echoed by increasing numbers of Latin, Greek, and Syriac writers in the late fourth century and afterward.