Marihuana use by pregnant women: neurobehavioral effects in neonates.

In a prospective study of 291 mothers-to-be, 20 per cent reported some use of marihuana before and/or during pregnancy. A significant increase in symptoms associated with nervous system abnormalities was observed among babies born to heavy regular marihuana users and visuals responses were affected in two- to three-day-old infants in a dose-related fashion. No relationship between marihuana use and maternal weight again, length of gestation, duration of labor or birthweight was found.