BackgroundNearly 5 % of pregnant women in the United States use cannabis. However, expecting mothers often do not seek counsel from their healthcare providers about prenatal cannabis use due to stigma and legal ramifications. Instead, cannabis-using pregnant women turn to each other to learn. Online message boards have become a safe place for parents to seek answers anonymously in real-time. The objective of this study was to examine the information-seeking/giving behaviors of cannabis-using pregnant women on an online community forum. MethodsWe extracted 151 original messages and 1260 corresponding comments posted over a 7-day period from Whattoexpect.com’s “Ganja Mamas” forum. We iteratively developed a codebook with 16 categories to reflect information-seeking behavior. N = 131 unique forum members posted questions for comment. ResultsApproximately half, 46.56 %, reported their geographic location (24 states), and 40.46 % reported gestational age. The top topics for which members sought out information were testing, state-specific questions, postpartum, child protective services (CPS), hospital-specific questions, birth announcements, methods of cannabis use, quitting, breastfeeding/pumping, pregnancy symptoms, mental health, general health and pregnancy, and quantity of cannabis use. The second phase of analysis was based on members' responses. Clustered codes indicated how the respondents were using the forum: (1) interviewing and geographic location, (2) knowledge, experience, and reassurance, (3) congratulations and relief, and (4) concealing cannabis use and symptoms. ConclusionsOur results demonstrate that mothers on an online cannabis forum are seeking information about location-specific experiences pertaining mostly to testing and child protective services. Additionally, mothers are responding by geographic-specific interviewing, and are expressing relief and reassurance in response to members’ experiences.