According to the church, any sexual positions other than what is now termed the "missionary position" (with the man lying on top of the woman) could not be condoned and were considered "unnatural." There were fears of reversing the natural order of male and female sexuality by having the female on top, in the superior or active role normally reserved for men. Intercourse a tergo, or from the rear, implied a similar threat; it was considered "beastly," and thus it confused the boundaries between human and animal behavior (Brundage, "Sex and Canon Law," 40).

    Anal and oral sexual practices were also considered unacceptable to Church authorities, but for a slightly different reason. These were seen as acts against nature, not because they interfered with standard male and female roles during intercourse, but because neither could possibly lead to procreation, which was considered the primary - and according to many purists the only - purpose of sexual interactions. Anal and oral intercourse were simply a means for sexual gratification, which the majority of canonists and theologians viewed as sinful in itself.

    Some strange opinions existed regarding non-standard positions that could in fact lead to procreation (such as sex from behind). For example, suggestions that children conceived in "unnatural" positions might experience birth defects was a common notiont during the middle ages.

    As for punishments inflicted on those engaging in sexual intercourse in deviant positions, the earlier Penitentials (handbooks for confessors) had some very harsh suggestions: three years' penance for the woman on top and the same for both oral intercourse and sex a tergo, which was generally seen as the most sinful position, anal intercourse excepted.