Sex and Contraception: A Tangled Relationship

Unintended pregnancies constitute a major public health challenge in most – developing and developed - countries, yet there is no convincing theory to explain their occurrence. Existing theoretical explanations are largely ad hoc, and surprisingly pay little attention to sex, the raison d'e ̂tre for contraception. This paper develops a theory of contraception based on sex and the degree of undesirability of the consequences of sexual activity. Defining sexual activity in terms of the human sexual response cycle, we note that sex is motivated by a desire for sexual pleasure, social relationships, and procreation. Variation in the desirability of these three consequences of sex, along with clear differences in the timing of their appearance, and differences in the uncertainty of their occurrence, provides the relevant sexual context for contraceptive use. While contraception is clearly aimed at avoiding conception, its underlying reasons may be very specific (health or desired family size) or non-specific and aimed quite simply at maintaining existing life styles. We model these aspects of sex and contraception using a model of human behaviour wherein behaviour and its constitutive actions are the result of varying degrees of deliberation; some more reflexive, others more reflective.