While attention deficit hyperactivity disorder is common among people with addiction, the risks and benefits of attention deficit hyperactivity disorder medication in pregnant people with opioid use disorder are poorly understood. Here, using US multistate administrative data, we examined 3,247 pregnant people initiating opioid use disorder treatment, of whom 5% received psychostimulants. Compared to peers not receiving psychostimulants, the psychostimulant cohort had greater buprenorphine (adjusted relative risk 1.81 (1.50-2.18)) but lower methadone initiation (adjusted relative risk 0.39 (0.19-0.78)). Among psychostimulant recipients who initiated buprenorphine, we observed lower buprenorphine discontinuation associated with the psychostimulant cohort compared to nonrecipients (adjusted hazard ratio 0.77 (0.67-0.88)). In within-person case-crossover analyses, person-days defined by psychostimulant fills were associated with fewer substance use disorder-related admissions compared to days without fills (odds ratio 0.50 (0.33-0.76)). Overall, our data suggest that psychostimulant use in pregnancy may be associated with increased buprenorphine initiation, decreased methadone initiation and improved buprenorphine retention. Decreased substance use disorder-related admissions were associated with person-days of psychostimulant receipt, although other risks of psychostimulant use in pregnancy warrant further investigation.