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To answer this question, I’m going to break down what the research says about cannabis use while breastfeeding while ultimately answering the all important question,  Is it okay to use medical marijuana while breastfeeding?


So, let’s start with the question,


Does THC pass into breast-milk?

The long and short of it is that THC does pass into breast-milk.


How much THC passes into breast-milk?

To answer this question, let’s take a look at the results of a study done very recently in 2018.  Now, in this particular study, they looked at how much THC passed into the breastmilk of nursing moms who inhaled cannabis.

The moms, who were 2 to 5 months post-partum, were instructed to inhale .1 g of cannabis containing 23.18% THC.  In other words, the moms inhaled just about 21.3 mg of THC.  And, then, samples of their breastmilk were collected at 20 min, at 1 hour, at 2 hours, and at 4 hours.  The breastmilk was analyzed.  In the end, it was found that breastfeeding infants would ingest 2.5% of the mom’s dose, which translates to an infant dose of 8 mcg/kg per day.


How long does THC stay in breast-milk?

It is not known how long it takes for THC to clear from breast-milk.  It’s important to know that how much and how long the different chemicals from marijuana stay in the body is different for each person.  Factors like, the strength of the marijuana product, the amount you use, how often you use it and how your body metabolizes the chemicals all play a role in determining how long the THC sticks around in breast-milk.

But what we do know is that infants exposed to marijuana through their mother’s milk will excrete THC in their urine for 2 to 3 weeks afterwards.


Can marijuana affect breastmilk supply?

In animals, THC has shown to decrease the amount of milk produced by suppressing the production of prolactin and, possibly, by affecting the mammary glands themselves.

Similarly, in human females, exposure of THC has been found to inhibit prolactin.

And, prolactin is a hormone that affects milk production.

So it’s possible that marijuana could affect breastmilk supply.


What’re the effects of marijuana on a breastfed baby?  

So, first thing is that a broad overview of the medical research on marijuana exposure while breastfeeding has shown the following adverse effects on infants,




Alright, having said that, now let’s take a closer look at several different studies to see how they  came to these conclusions.


STUDY #1:  Maternal marijuana use during lactation and infant development at one year.

One study from back in 1989 looked at the effects of marijuana through breast-milk on the mental and motor development in 68 infants.

On average, the moms smoked 1 joint at least once a week during lactation.

And, it was found that daily marijuana exposure via the mother’s milk at 1 month of age appeared to be associated with a decrease in infant motor development later on at 1 year of age.

But, the moms’ use of marijuana during lactation had no detectable effect on the infants’ mental development at 1 year of age.

The other important point to note is that infants exposed to marijuana via mother’s milk at the three-month mark did not show decreased motor or mental development later on at 1 year of age.

Overall, here’s what the researchers ultimately said,

“In summary, although marijuana exposure during lactation was associated with decreased infant motor development, this result should be interpreted cautiously due to the preliminary nature of this study. One cannot infer from the results presented here that marijuana exposure during lactation impairs motor development at one year of age… Marijuana exposure during lactation seemed to be a better predictor of infant motor development, but that does not necessarily mean that the relationship is one of cause and effect.”


STUDY #2:   Marijuana: prenatal and postnatal exposure in the human.

Another study from 1985 also looked at the effects of marijuana exposure during breastfeeding.  62 of the infants seen at 1 year of age had been breastfed. Of these, 27 of the mothers reported using marijuana during breastfeeding; 12 of them smoked once a month or less, 9 smoked weekly, and 6 smoked daily.

In the end, the study found no apparent effects of marijuana exposure on infant growth, or on mental and motor development.


What’s the overall consensus on using medical marijuana while breastfeeding?  

The American College of Obstetrics and Gynecology – these are the folks who pretty much lay down the law on the standards of practice for Obstetricians and Gynecologist – say that there’s just not enough information to evaluate the effects of marijuana use on infants during lactation and breastfeeding, and in the absence of such information, they discourage marijuana use for breastfeeding moms.

And, honestly, I’d have to say I agree.  My objective is to help, not harm, and if there’s the possibility of harm to growing infant, then it just doesn’t make sense to recommend medical marijuana use to breastfeeding moms.

Alright there you have it, an answer to the question, Is it okay to use medical marijuana while breastfeeding?







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