en español

Marijuana and Pregnancy

How does marijuana affect pregnancy?

Marijuana crosses the placenta. We also know that the endocannabinoid or endogenous
cannabinoid system is active during pregnancy implantation and fetal development. Therefore,
there are concerns that consumption of marijuana (eg exogenous cannabis) during pregnancy
may have adverse effects on the pregnancy.

What do the studies show?

There are many studies available about marijuana in pregnancy. Unfortunately the available data
are somewhat mixed with regard to pregnancy outcomes which has led to confusion among
pregnant women and healthcare providers. Many people have worked to summarize the available
evidence including public health groups and researchers. When studies of marijuana in pregnancy
are combined, it appears that there is an association between marijuana use and poor fetal
growth. There is also increasing concern regarding higher risk of neonatal intensive care unit
admission among exposed babies. In addition, there are some animal and human studies
demonstrating an adverse effect on fetal neurological development. More research needs to be
done. But given the concern for harm, women should not use marijuana during pregnancy.

What about breastfeeding?

The data for breastfeeding are more limited. The few available studies demonstrate that
marijuana metabolites are present in the breastmilk following maternal use. Unfortunately, we
do not know how long metabolites are present. Therefore we cannot offer a safe amount of time
to “pump and dump” after maternal use to avoid exposure to the neonate. Women are
encouraged not to use marijuana when breastfeeding.


Women should speak with their healthcare providers if they are using marijuana during
pregnancy. Often women are using marijuana because of the perception that it is improving a
medical condition. There are no high quality studies demonstrating efficacy of marijuana for
treating medical conditions during pregnancy. In many cases, there are safe and effective
alternatives that can be offered. The Colorado Dept of Health and Environment has launched a
campaign called Good to Know Colorado. This campaign is directly primarily at adolescents and
at reproductive age women in order to help with understanding the potential harms of marijuana
use during pregnancy.