No Increased Risk Found
"In the OPPS [Ottawa Prenatal Prospective Study], no association with marijuana use and subjects’ miscarriage rates, types of presentation at birth, Apgar status, and the frequency of neonatal complications or major physical abnormalities (Fried 1982; Fried et al. 1983) were found. No patterns of minor physical anomalies were noted among the offspring of marijuana users although two anomalies, true ocular hypertelorism and severe epicanthus, were observed only among children of heavy users of cannabis (O’Connell and Fried 1984). In general, researchers have not reported an association between prenatal marijuana use and morphologic abnormalities in offspring (e.g., Day et al. 1991) and, as reviewed elsewhere (Dalterio and Fried 1992; O’Connell and Fried 1984), the few reports of increased physical abnormalities may reflect a lack of control for confounding factors (e.g., prenatal exposure to alcohol) and/or the relative risk status of the women in the study."
Fried, Peter A., "The Consequences of Marijuana Use During Pregnancy: A Review of the Human Literature," Journal of Cannabis Therapeutics (London, United Kingdom: Haworth Integrative Healing Press, 2002) Vol. 2, No. 3/4, p. 86.