Marijuana can be healthier than other drugs, and it can treat symptoms like nausea in pregnant women. However, research suggests that it might not be a good idea for pregnant women to use marijuana. More specifically, the THC in marijuana can damage a baby’s brain in ways the parents might not notice until they are older.

American Congress of Obstetricians and Gynecologists will say no if you ask whether it is safe to use marijuana during pregnancy. “Although there are limitations to the data on marijuana use during pregnancy…worrisome trends do emerge,” they said. Infants who were exposed to marijuana in utero have a high tendency of having cognate and behavioral problems later in life. Experts definitely do not recommend smoking marijuana if you are pregnant. Here are the details.

The best known marijuana component is tetrahydrocannabinol(THC). It’s the major psychoactive component, which makes you high. THC circulates in your blood and can cross the placenta. As a result, the fetus is exposed to it as well. THC is also fat-soluble, and can end up being mixed into your body fat. Therefore, even if you do not consume any marijuana, there can still be THC in your body.

THC can also mix with breast milk, and its metabolites will be in baby poop. Hence, the child is exposed to THC if you use marijuana and also breastfeed.

All the research on marijuana comes from studies in which scientist use animals like rats as subjects. Diana Dow-Edwards, a scientist who does animal research on how drugs affect the developing brain, says it is proven that THC interferes with the way brain cells connect to each other. “This of course is the whole essence of the brain,” she says. “One neuron connects to the next neuron, which connects to the next.” The more THC the brain is exposed to , the greater the effect on the connections.

Human brain cells develop in a similar way to those in rodents, however, we need real-world studies to find out what this means for human beings. It is not ethical to do an experiment on human, since the study would force some women the smoke marijuana in pregnancy. As a result, researchers observe women who decided on their own to smoke weed in pregnancy, and compare their children with those whose mothers who did not smoke weed in order to find out the effect.