Barriers to adolescent adherence to contraception: Knowledge of depo provera timing

Background: Depo Provera is a long-acting progestin contraceptive method that is both highly effective and safe. However, continuation rates at one-year range from 30–42%. It has been suggested that one common reason for discontinuation is poor adherence with appointments. Poor adherence could be related to lack of knowledge regarding the timing of the next injection. Therefore, the purpose of the current investigation was to examine whether adolescent girls were knowledgeable about when their next injection was due. Methods: Adolescent girls were recruited from an urban-based adolescent clinic to participate in a longitudinal study of psychosexual development. The girls were seen every 6 months over three years. At the last three visits, those adolescents on Depo Provera were asked when their next injection was due. Responses were coded as accurate if the date given was within 10–14 weeks of the last injection. Results: There were 45 girls who were using Depo Provera and seen for at least one study visit. The girls ranged in age from 15–19 years, and 87% were African-American; the remainder were Caucasian. 22 girls were seen/and on Depo Provera for 1 visit, 12 for 2 visits, and 11 for 3 visits. Collapsing their answers across visits, 27 of girls were always correct, 11 were sometimes correct, and 7 were never correct. Race and age were not related to whether they were always correct, sometimes correct, or never correct. At the last visit, we examined whether or not length of time on Depo Provera was related to correctness. The relationship appeared to be curvilinear. That is, those girls who had been on Depo Provera the longest time (⩾ 18 months) and the least (< 6 months) time were most likely to be correct. Conclusions: This study demonstrates that many (40%) adolescents do not know when their injection is due, and in fact, the correctness of adolescents' knowledge is not consistent over time. Age and race were not significantly related to knowledge of timing. Therefore, ALL adolescents should be provided with reminders about the timing of their next injection. Finally, the curvilinear relationship needs to be examined further. This finding that adolescents on Depo Provera for 6–12 months were the least knowledgeable is consistent with research on oral contraceptive adherence indicating this is a vulnerable time period for contraceptive discontinuation.