Young Women's Complex Patterns of Contraceptive Use: Findings from an Australian Cohort Study.

Context: Unintended pregnancy is common among young women. Understanding how such women use contraceptives- including method combinations-is essential to providing high-quality contraceptive care.

Methods: Data were from a representative cohort of 2,965 Australian women aged 18-23 who participated in the 2012-2013 Contraceptive Use, Pregnancy Intention and Decisions baseline survey, had been heterosexually active in the previous six months, and were not pregnant or trying to conceive. Latent class analysis was employed to characterize women's contraceptive choices; multinomial logistic regression was used to evaluate correlates of membership in the identified classes.

Results: The vast majority of women (96%) reported using one or more contraceptives, most commonly short-acting hormonal methods (60%), barrier methods (38%), long-acting contraceptives (16%) and withdrawal (15%). In total, 32 combinations were reported. Four latent classes of method use were identified: no contraception (4% of women); short-acting hormonal methods with supplementation (59%, mostly the pill); high-efficacy contraceptives with supplementation (15%, all long-acting reversible contraceptive users); and low-efficacy contraceptive combinations (21%); supplementation usually involved barrier methods or withdrawal. Class membership differed according to women's characteristics; for example, women who had ever been pregnant were more likely than other women to be in the no-contraception, high-efficacy contraceptive or low-efficacy contraceptive combination classes than in the short-acting hormonal contraceptive class (odds ratios, 2.0-3.0).

Conclusions: The complexity of women's contraceptive choices and the associations between latent classes and such characteristics as pregnancy history highlight the need for individualized approaches to pregnancy prevention and contraceptive care.