Is it safe to use cannabis while pregnant or nursing? Cannabis can be very effective for the hyperemesis gravidarum (intractable vomiting) that sometimes accompanies pregnancy, but is it toxic for babies? What about the safety of using cannabis while breastfeeding? Melanie Dreher, PhD did some of the best work on this subject, studying a large number of pregnant women and babies in Jamaica, and her findings are reassuring. This article was published in 1994 in the Journal of Pediatrics.