Acceptability of different mechanisms of action of contraception in women: a questionnaire survey.

Background: The mechanism of action of a contraceptive method is an importantg consideration in a woman's choice of contraception. For the development of new methods of contraception it is important to understand the acceptability of different contraceptive mechanisms within a population.

Methods: We recruited women attending contraceptive, termination of pregnancy or postnatal care services in Hong Kong for a questionnaire survey on their acceptability of the different ways in which contraceptive methods prevent pregnancy. Univariable and multivariable analyses were used to establish factors which may predict acceptability of the mechanism of action.

Results: A total of 1448 women completed the survey. The acceptability of contraceptive methods that act by preventing fertilisation ranked highest (78%), followed by those that inhibit ovulation (52%), disrupt implantation (43%) and dislodge an implanted embryo (30%). A history of termination of pregnancy was associated with greater acceptance of all posited contraceptive mechanisms. There was a very low degree of agreement between the declared acceptance of the various contraceptive mechanisms and the ever use of a method with the respective mechanism of action (Cohen's kappa coefficient range 0.017-0.162).

Conclusions: In this population the acceptability of contraceptive methods that act by preventing fertilisation ranked highest, followed by those that inhibit ovulation, disrupt implantation and dislodge an implanted embryo. Women who had ever had a termination of pregnancy were more likely to accept all the posited contraceptive mechanisms.