Cannabis and Breastfeeding: What’s Safe and What’s Not

The intersection of cannabis use and breastfeeding is a complex topic that many parents are navigating today. As more people use cannabis for various reasons—whether for pain management, anxiety, or relaxation—questions about how it affects breast milk and, ultimately, the infant’s health have become increasingly common. But with limited data, and some studies that are decades old, it’s essential to rely on the best information available while keeping in mind that each situation is unique.

What We Know About THC and Breastfeeding

One of the main concerns surrounding cannabis and breastfeeding is the transfer of THC (tetrahydrocannabinol) into breast milk. However, the science on this subject is still developing, and the research primarily dates back to the 1970s and 1980s. While some studies from these decades suggest minimal THC transfer into breast milk, much of the data remains outdated, leaving gaps in our understanding of how cannabis affects breastfeeding.

Limited and Outdated Studies

A study conducted in the 1970s found that only 0.2% of the THC ingested by the mother was detected in breast milk in monkeys. While the data was limited even then, it provides a starting point for understanding potential THC levels in breast milk. The most recent study on this topic, conducted in 2018, adds some clarity to the issue, but the research sample size remains small.

More importantly, there is no study that isolates cannabis use as the sole factor affecting infant health during breastfeeding. Other elements, such as diet, environmental factors, and overall maternal health, can also play a role.

THC Transfer and Its Minimal Impact

Recent studies suggest that the transfer of THC into breast milk occurs in very low amounts—measured in nanograms. This means the concentration is exceedingly small, often well below levels that would cause harm to an infant, though it’s still important to exercise caution.

One study examined two heavy marijuana users and found THC levels in their breast milk of 105 ng/mL and 340 ng/mL. While these concentrations might seem significant at first glance, they are not representative of the broader population, as the sample size was small and both mothers were regular, daily cannabis users. Additionally, the study did not account for factors such as the amount of cannabis consumed or the time between consumption and milk sampling, which are critical for accurate interpretation.

Factors That Affect THC Levels in Breast Milk

Several factors can influence the amount of THC in breast milk, including:

• Frequency of cannabis use: Daily users accumulate THC in their bodies, particularly in fat tissues, which can then transfer to breast milk.

• Time since consumption: THC levels are higher immediately after consumption, with the highest concentrations typically seen about 1-2 hours after use. Over the course of 4-6 hours, THC concentrations drop significantly in breast milk.

• Inhalation vs. ingestion: When cannabis is smoked or vaporized, THC enters the bloodstream more quickly, resulting in higher immediate concentrations in breast milk. In contrast, ingested cannabis has a lower bioavailability due to the liver’s first-pass effect, meaning less THC reaches the bloodstream and, ultimately, the milk.

  
  

How Long Does THC Stay in Breast Milk?

The half-life of THC in breast milk is roughly 24 hours, meaning it takes around a day for the THC levels in breast milk to decrease significantly. However, this can vary depending on how often a person uses cannabis, their metabolism, and other factors.

It’s also worth noting that the relative infant dose (RID) of THC in breast milk is very low—about 2.5, which is 1000 times lower than the adult dose. This means that even if THC is transferred to the baby through breast milk, the amount is exceedingly small.

Timing Cannabis Consumption to Minimize THC Exposure

While the THC concentrations in breast milk are generally low, there are ways to reduce potential exposure to the infant:

• Feed before consumption: One strategy is to breastfeed just before using cannabis, ensuring that the baby isn’t exposed to THC during its peak concentration in the milk. By the time the next feeding occurs—typically several hours later—the THC levels in the milk will have decreased significantly.

• Pumped milk: Some parents choose to pump and store milk in advance of cannabis use, giving the baby pumped milk during the first feed after consumption. This reduces the likelihood of THC exposure in the early stages after use.

• Formula feeding: As a last resort, some parents use formula for the first feeding after cannabis consumption. However, this should not become a regular practice, as it can interfere with the benefits of breast milk.

Considerations for Premature Babies and THC

While most studies indicate minimal harm from THC in breast milk, there’s still concern for preterm neonates, whose systems may be more sensitive. A study conducted between 2014 and 2020 focused on early preterm infants in a Level IV NICU. It found no significant differences in health outcomes (e.g., growth, oxygen requirements) between babies exposed to THC through breast milk and those who were not. Still, more research is needed to understand the potential effects of cannabis on preterm infants.

What Parents Should Keep in Mind

If you're a parent who uses cannabis and is breastfeeding or chestfeeding, it’s essential to make informed decisions. Here are some tips to consider:

• Trust your instincts: Pay attention to how your baby behaves and develop an understanding of their feeding and sleeping rhythms. If you have concerns, reach out to your pediatrician or a cannabis-informed healthcare provider for guidance.

• Avoid getting "too high": Being unable to care for your baby because you are too impaired is a safety concern. Always use cannabis responsibly, and consider how it may affect your ability to care for your child.

• Smoke-free environment: Never smoke cannabis around your baby. Secondhand cannabis smoke can have its own risks, just as tobacco smoke can.

Cannabis Doula Support

If you are considering using cannabis during pregnancy, childbirth, or postpartum, a cannabis doula may be able to provide valuable support. Cannabis doulas specialize in offering non-judgmental, evidence-based guidance to help families navigate cannabis use in a safe and informed way. They work alongside healthcare providers to discuss potential risks and benefits, legal considerations, and other aspects of using cannabis in a responsible and supportive environment.

Conclusion

The current research on cannabis use during breastfeeding is still limited, and while the evidence suggests that THC transfer to breast milk is minimal, it’s always best to proceed with caution. By timing cannabis consumption, avoiding secondhand smoke, and using resources like cannabis doulas, you can make informed decisions that support both your health and your baby’s well-being. As research evolves, we will continue to learn more about the full impact of cannabis use during breastfeeding.