Results:
We identified 23 eligible studies in this review, involving 9474
pregnant people and 613 postpartum or unspecified people. These studies
were conducted in jurisdictions where cannabis was legal, decriminalized
and illegal. Most studies were conducted in the United States of
America, where states have varying cannabis laws, but cannabis remains
federally illegal.
Concerning quality appraisal, the MMAT tool discourages the calculation
of an overall score from the ratings of each category, but the quality
of included papers was mostly acceptable 42. As
recommended, we present the rating for each criterion in Table 2 for the
purposes of evaluating the strength of the conclusions of this
synthesis. The included studies represent a variety of methodological
approaches with roughly equal distribution of qualitative, quantitative,
and mixed methods approaches (Table 4). The combined study populations
of 10,087 were dominated by Oh et al 2017 52 which had
7627 participants. No partners were included in these studies and none
of the postpartum participants were sampled for their experience or
perspectives on using cannabis while breastfeeding (Table 4).
Accordingly, our review of partner perspectives and the perspectives of
lactating people is empty.
Our initial analysis of the entire dataset identified divergent findings
across papers, and this divergence was not associated with critical
appraisal results. As we engaged in comparative analysis, we identified
that much of the divergence was accounted for by the other substances
included in the study. When cannabis was studied alone, grouped with
alcohol or tobacco, or grouped with other drugs, the focus and hence the
findings of each study shifted. Accordingly, we present findings
according to comparator groups (Table 5). We present a synthesis of
evidence on three main themes that emerged through our inductive
analysis: the main decisions faced by participants in these studies;
descriptions of risk and benefit; descriptions of how information was
sought and used (Table 6).