Daily intentions may shape cannabis use during pregnancy

Perinatal cannabis use is a significant public health concern linked to adverse maternal and neonatal outcomes. Despite growing evidence of prenatal cannabis use (PCU) risks, many individuals use it to manage symptoms such as nausea, anxiety, or pain. The Theory of Planned Behavior (TPB) identifies intentions as key predictors of substance use. While intentions and use patterns have been well studied in non-pregnant populations, research on prenatal intentions for cannabis use is limited. This pilot ecological momentary assessment (EMA) study examines: (a) cannabis use and non-use days in terms of intentions and use; (b) associations between daily intentions and use across prenatal and postpartum; and (c) motives linked to planned versus unplanned use. Pregnant participants (N = 20; Mage = 30.15) reporting current prenatal CU completed two 14-day EMA bursts (in pregnancy and at 6-weeks postpartum) tracking daily CU, motives, and intentions. Planned use days were coded based on morning endorsement of intention to use, followed by reported use; unplanned use days were coded based on no morning intention, followed by reported use. Planned use was most common both in pregnancy and postpartum, followed by planned nonuse, unplanned use, and foregoing plans to use. Intentions strongly predicted daily cannabis use (OR = 5.78, p < .001), with no significant difference between pregnancy and postpartum. Common motives across both planned and unplanned days included relaxation, pain relief, and sleep improvement. Some motives, including appetite increase and anxiety reduction, were more frequent on planned days, while enhancement motives were more common on unplanned days. Findings support TPB's relevance to perinatal cannabis use, highlighting distinct motives for planned versus unplanned use. Larger samples are needed to expand these insights.