Contraceptive Behavior Dynamics and Unintended Pregnancy: A Latent Transition Analysis.

The average U.S. woman wants to have two children; to do so, she will spend about three years pregnant, postpartum, or trying to become pregnant, and three decades trying to avoid pregnancy. However, few studies have examined individual patterns of contraceptive use over time. These trajectories are important to understand given the high rate of unintended pregnancy and how little we know about the complex relationship between contraceptive use, pregnancy intention, and patterns of reproductive behavior. We use data from the 2015-2017 National Survey of Family Growth to examine reproductive behavior and pregnancies across three years of calendar data. We identify seven behavior typologies, their prevalence, how women transition between them, and how pregnancies affect transitions. At any given time, half of women are reliably using contraception. A small proportion belong to a high pregnancy risk profile of transient contraceptive users, but some transition to using condoms or other methods consistently. An unintended pregnancy may initiate a transition into stable contraceptive use for some women, although that is primarily condom use. These findings have important implications for the ways contraception fits into women's lives and how that behavior interacts with relationships, sex, and life stage trajectories.