Causal effects of cannabis legalization on parents, parenting, and children: A systematic review.

ABSTRACT

Medical and recreational cannabis legalization lead to increased cannabis use among adults. There is concern that legalization has negative implications for minors via effects on parents. We conducted a systematic review of studies examining legalization in the United States. Web of Science, PsycInfo, and PubMed were searched through May 2021, studies examining effects of legalization on maternal cannabis and other substance use during pregnancy and postpartum, perinatal outcomes, parental cannabis and other substance use and attitudes, parenting, and child outcomes were identified, and two independent reviewers extracted information on study designs, samples, and outcomes, and assessed classification of evidence and risk of bias. Forty-one studies met inclusion criteria; only 6 (15%) used the most causally informative study design (difference in differences). It is likely legalization increases maternal cannabis use during pregnancy and postpartum, parental cannabis use, and approval of adult cannabis use. Legalization may increase some adverse perinatal outcomes, though findings were inconsistent. It is likely legalization increases unintentional pediatric cannabis exposure. There is insufficient evidence for effects of legalization on child abuse and neglect, and there have been no studies examining effects of legalization on other aspects of parenting or on child adjustment. There is a critical lack of causally informative epidemiological studies examining effects of legalization on parenting and young children. Additional causally informative research is needed. Studies of parental cannabis use in a legal context are particularly needed. Commonsense guidelines must recognize the shifting national landscape around legalization while seeking to minimize potential harm to minors.