Effects of marijuana use during pregnancy and breastfeeding

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Studies suggest that using marijuana while pregnant or breastfeeding may have negative affects on the baby’s development. While these studies have been limited so far, the Northern New England Poison Center recommends avoiding marijuana use if you are pregnant, planning to become pregnant, or breastfeeding.

Marijuana Use During Pregnancy

THC, the chemical in marijuana that causes the high, crosses the placenta into the fetus during pregnancy. Babies exposed to THC in the womb may have some increased risks.

  • Birth defects. The baby may be more likely to have defects related to:
    • Brain and skull development
    • Heart development
    • Development of the esophagus, intestines and diaphragm
  • Premature birth. The baby may:
    • Be born early
    • Have a low birth weight
    • Need special hospital care
  • Behavior and learning problems in life. These can include:
    • Hyperactivity
    • Impulsiveness
    • Inattention
    • Trouble with reading and spelling
    • Trouble with abstract reasoning and visual problem solving

Marijuana Use While Breastfeeding

THC enters breast milk and will be passed on to the baby when breastfeeding. Even after stopping use, marijuana will remain in the milk for days. Pumping and dumping may lower the baby’s THC exposure but it will not eliminate it.

It’s unclear at this time what effect marijuana use while breastfeeding has on a child’s long-term development.


There is not enough research to say for sure how marijuana use in pregnancy or while breastfeeding will affect the baby. Findings are often based on small numbers of people, and many mothers in the available studies also smoked tobacco, drank alcohol or used other drugs. The effects of use while breastfeeding are especially hard to single out because many mothers also used marijuana during pregnancy, which likely has a larger effect.

However, there is enough evidence of possible negative effects that the American College of Obstetricians and Gynecologists recommends that marijuana be avoided during pregnancy. In addition, it is best for women who are breastfeeding to avoid using marijuana because of the possible negative effects.

Further Reading

Ryan, S.A., et al., Marijuana Use During Pregnancy and Breastfeeding: Implications for Neonatal and Childhood Outcomes. Pediatrics, 2018. 142(3).

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