Development and Validation of the Cannabis Exposure in Pregnancy Tool (CEPT)

Background Evidence of associations between prenatal cannabis use (PCU) and maternal and infant health outcomes remains conflicting amid broad legalization of cannabis across Canada and 40 American states. A critical limitation of existing evidence lies in the non-standardized and crude measurement of PCU, resulting in high risk of misclassification bias. We developed a standardized tool to comprehensively measure prenatal cannabis use in pregnant populations for research purposes. Methods We conducted a patient-oriented tool development and validation study using a bias-minimizing process. Following an environmental scan and critical appraisal of existing prenatal substance use tools, we recruited pregnant participants via targeted social media advertising and obstetric clinics in Alberta, Canada. We conducted individual in-depth interviews and cognitive interviewing in separate sub-samples, to develop and refine our tool. We assessed convergent and discriminant validity internal consistency and 3-month test-retest reliability, and validated the tool externally against urine THC bioassay. Results 254 pregnant women participated. The 9-item Cannabis Exposure in Pregnancy Tool (CEPT) had excellent discriminant (Cohen’s kappa=-0.27-0.15) and convergent (Cohen’s kappa=0.72-1.0) validity; as well as high internal consistency (Chronbach’s alpha = 0.92), and very good test-retest reliability (weighted Kappa=0.92, 95% C.I. [0.86-0.97]). The CEPT is valid against urine THC bioassay (sensitivity=100%, specificity=77%). Interpretation The CEPT is a novel, valid and reliable measure of frequency, timing, dose, and mode of PCU, in a contemporary sample of pregnant women. Using CEPT (compared to non-standardized tools) can improve measurement accuracy, and thus the quality of PCU and maternal and child health research. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This project was funded by a competitive research grant from the Alberta Children's Hospital Research Institute, University of Calgary. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Conjoint Health Research Ethics Board at the University of Calgary gave ethical approval for this study (REB19-0670). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All quantitative data produced in the present work will be available upon reasonable request to the authors, within ethical constraints upon completion of analyses. Qualitative data cannot be released for ethical reasons.