During pregnancy, women who smoke marijuana expose their developing fetuses to the drug when it passes to the fetal bloodstream inside the placenta. There is considerable disagreement among medical professionals about the impact of marijuana on fetal development, in part because women who use the drug also commonly use other substances that can alter the development process. Still, current evidence indicates that use of marijuana during pregnancy can potentially produce negative effects on the viability of that pregnancy, as well as negative effects on the long-term learning capabilities of children exposed to the drug in the womb.
