Project Summary/Abstract Because most people return to sexual activity shortly after giving birth, consistent use of effective contraception is critical to achieving healthy birth spacing. Healthy birth spacing could be dramatically improved at the population level by increasing the proportion of postpartum patients who receive and continue use of very effective contraceptive methods (including any method with less than a 10% typical use failure rate) after birth. However, data are lacking regarding what knowledge and attitudinal factors drive pregnant people’s intention to use contraception after birth. Additionally, not all individuals who form an intention to use contraception postpartum end up being able to act on that intention after birth. It is unknown what specific environmental barriers prevent patients from receiving desired contraception postpartum. This study will fill the evidence gap around drivers of postpartum contraceptive use by achieving the following aims: Aim 1: Clarify the role of contraceptive knowledge, attitudes, norms, and self-efficacy in driving intention to initiate very effective contraception (VEC) postpartum. We will enroll pregnant patients at two large academic medical centers with medically and demographically diverse patients, and query them through a baseline survey regarding factors that influence intention to use contraception postpartum. Aim 2: Describe the impact of environmental barriers on enacting intended postpartum VEC initiation. Using a sequential mix-methods design, we will explore how the effect of intention on actual postpartum VEC initiation varies by environmental factors. Quantitative data will be collected from an electronic medical record review and a 12-week postpartum patient survey, and qualitative data through interviews of select participants who faced significant barriers in attempting to initiate postpartum contraception. We will conduct formal statistical tests of effect modification to quantify how environmental factors modify the effect of planned VEC initiation on actual initiation. Qualitative interviews will additionally explore the processes through which patients experience, interpret, and respond to environmental barriers. This study is innovative because of its novel grounding in behavioral theory, prospective design enabling testing of hypothesized behavioral-environmental drivers of outcomes, and mixed-methods approach to developing future interventions to improve population health by increasing healthy birth spacing. This project will be impactful because findings will lead directly to development of 1) an evidence-based approach to antenatal counseling about postpartum contraception that will increase intention to use VEC, and 2) recommendations for interventions at the health system level to ameliorate structural barriers that impede postpartum patients’ ability to act on that intention. Results will be disseminated to lay community health advocates and clinical leaders...