Marijuana Use During Pregnancy and Breastfeeding

What the actual risks are

THC (the psychoactive component of cannabis) crosses the placenta and can affect fetal development. Research links prenatal cannabis exposure to lower birth weight, and to later childhood differences in attention, memory, problem-solving, and behavior regulation. The CDC's position is direct: cannabis may be harmful to a developing baby no matter how it's used — smoked, vaped, or eaten.

This is genuinely still an area of active research, and not every study finds the same effect size — but no major health authority has identified a use pattern or amount shown to be safe, which is different from most over-the-counter medications, where a clear safe-dose range does exist.

During pregnancy: the current recommendation

The CDC recommends not using marijuana at all during pregnancy, whether the use is recreational or for a specific symptom like nausea or pain — there's no established safe threshold, dose, or frequency. This recommendation doesn't change based on whether cannabis is legal in your state; legality and prenatal safety are separate questions.

CBD-only products aren't automatically a safer substitute. Most aren't well-regulated, product labels aren't reliably accurate about what's actually in them (including trace THC), and CBD itself hasn't been well-studied in pregnancy either — "CBD, not THC" isn't the same as "verified safe."

Breastfeeding is a related but separate question

THC does pass into breast milk. Because THC is fat-soluble, it's stored in body fat and released gradually over time — which means, unlike alcohol, a single use doesn't clear from milk on a predictable, short timeline. Current guidance recommends avoiding cannabis while breastfeeding for the same underlying reason as during pregnancy: no safe amount has been established for a developing infant.

If you smoke or vape around your baby, secondhand smoke exposure of any kind is worth avoiding regardless of what's being smoked — that's a separate consideration from what shows up in breast milk itself.

If you're currently using and pregnant or breastfeeding

Stopping or cutting back matters at any point, not only before conception — this isn't all-or-nothing, where finding out later means the conversation isn't worth having. If you're using cannabis to manage a real symptom (chronic pain, severe nausea, anxiety, sleep), that's worth naming directly, since there are often other options worth trying rather than a choice between untreated symptoms and continued use.

Talking to your provider

Being honest about actual use — how often, in what form, and why — lets your provider give accurate, specific guidance instead of generic advice, and lets them plan appropriately for your baby's care after birth. Screening and reporting policies around substance use in pregnancy vary by state and by practice, so if that's a real concern for you, it's fair to ask your specific provider directly what their policy is rather than assume either way going in.