Background <p>Medications for opioid use disorder (MOUD) with methadone or buprenorphine are the standard of care for opioid use disorder (OUD) during pregnancy and postpartum. MOUD is not routinely available in US jails. Little is known about OUD management practices and patient experiences when MOUD is unavailable in jails. This study aims to assess deviations from standard pregnancy OUD care in jail and demonstrate patients’ experiences of such deviations.</p> Methods <p>Mixed-methods, secondary analysis from two prior studies: (1) a survey of US jails (<i>n</i> = 836) regarding availability MOUD in pregnancy and (2) interviews with pregnant and postpartum people with OUD (<i>n</i> = 32) who were in jail while pregnant. We analyzed survey results using descriptive statistics and interview transcripts using directed content analysis. We triangulated practices across both studies and grouped them thematically.</p> Results <p>Practices deviating from the standard of care included: use of naltrexone in pregnancy (<i>n</i> = 111), MOUD discontinuation postpartum (<i>n</i> = 489), and use of acetaminophen/codeine as maintenance therapy (<i>n</i> = 5). Interviewees described a lack of counseling and choice in MOUD, frequent opioid withdrawal, and inadequate withdrawal management.</p> Conclusions <p>Deviations from standard pregnancy OUD care are common in jail. Since the lack of MOUD and opioid withdrawal increases overdose risk and other adverse perinatal outcomes, we must address substandard care in jail for this population.</p>