Tags:  Lactation; breast milk; cannabis; child development

 

Thumbnail: Using cannabis while breastfeeding puts infants at risk of exposure to cannabinoids and their metabolites through breast milk. Based on this, guidelines argue that women should abstain from cannabis use when they’re breastfeeding, or at least reduce consumption if abstinence is not possible. These guidelines also recommend that women who use cannabis while breastfeeding should avoid nursing within 1 hour of inhaled use to reduce exposure to the highest concentrations of cannabinoids in breast milk.

 

The problem: One active ingredient in cannabis, THC, accumulates to high concentrations in breast milk.  This means that nursing infants can be acutely exposed to high levels of THC while feeding, and we don’t know what potential impact that might have on their development.

 

The study: The authors performed a thorough review of the literature to evaluate evidence regarding the effects of exposure to cannabis in breast milk on infants. Using this, the authors provide evidence-based clinical advice for breastfeeding women about the safety of infant exposure to cannabis during lactation.

The literature review spanned 171 articles from three databases (Medline, Embase, and PsychInfo), dating from their start until July 2018. Articles were screened for those that addressed the impact of postpartum cannabis use by lactating women, and which studied developmental outcomes for infants.  Only two articles met these criteria and were included in this review. Both studies recruited women during pregnancy and conducted postpartum evaluations of developmental outcomes (both mental and motor) associated with infant exposure to cannabis in breast milk.

 

Main results:

• A total of 150 mother-infant pairs were included, between the two studies

• One study found that there were no significant differences in the mental or motor development of infants on the basis of post-natal cannabis exposure

• This study also found that comparisons based on the level or length of prenatal cannabis exposure did not show any association between maternal prenatal cannabis use and infant developmental scores

• The second study found that average motor development scores were significantly lower for infants who had been exposed to cannabis for more than half of the first trimester of pregnancy or during the first month of lactation, but use during the third month of lactation did not have a significant impact.

• Both studies agreed that maternal cannabis use during pregnancy and lactation was not associated with differences in infant mental development at 1 year of age

• The two studies had different findings with respect to cannabis effects on motor development- one did not find any difference in development, while the other reported a difference in development depending on the level of cannabis exposure

• Clinical recommendations based on these studies:

  • Pregnant women should be counseled about potential risks of postpartum cannabis use to infant health, including shorter duration of breastfeeding and possible neuro-developmental delays.

  • Women who are breastfeeding should be advised to abstain from cannabis use and other co-exposures such as alcohol and tobacco during lactation.

  • If abstinence is not possible, mothers should be advised to reduce cannabis use

  • To reduce the risk of exposure to the highest concentration of THC in breast milk, women should avoid breast- feeding within 1 hour of inhaled cannabis use

 

Conclusions:  There is some evidence that cannabis use during nursing can have a detrimental effect on infant development. However, the results are inconsistent across studies and this review highlights this gap in the field.  In order to develop the best recommendations for cannabis use while nursing, the possible effects of infant exposure to THC in breast milk need to be more thoroughly investigated.

 

Why this is a good study:

• The authors thoroughly screened the available literature relevant to the topic, so this is a pretty complete survey of existing data.

• This is clearly and understudied area, so this review is important in bringing attention to this oversight.

 

Why this isn’t a perfect study:

• Many mothers in these studies reported use of substances like alcohol, cocaine, etc. in addition to cannabis, so the study couldn’t separate the effects of cannabis alone from potential confounding effects of multiple substances.

• The findings did not completely separate effects from pre- or postnatal exposure (most mothers who used cannabis while nursing, had also used it during pregnancy), so it is not clear which is the stronger determinant of infant development.

• Both studies took place in the 1980s, and the potency and composition of cannabis strains has changed since then.Much of this use was likely illegal, and involved products without adequate quality control.Therefore, these results may not accurately reflect the risks posed by exposure to legal cannabis today.

• These studies only followed the infants up to 1 year of age, therefore we don’t know if there may be longer-term impacts or what those effects might be.

 

What this study adds:

• This study highlights the need to study the potential effects of cannabis in breast milk on infant development

• This study suggests that women ought to be very cautious if choosing to use cannabis while pregnant and nursing

 

What it doesn’t:

• This is a retrospective study, conducted on women using strains of cannabis that are likely not in circulation any more- this is unlikely to provide an accurate picture of what effects current strains may have

• There are a number of confounding factors to be considered here.These current guidelines are recommendations, but without more thoroughly studying this topic, we can’t say for sure how much of a danger this may pose to infants

 

 

Funder:  No agency funding was reported.

 

Author conflicts:  Dr. Ordean has received honoraria for presentations and development of educational materials relating to substance use in pregnancy.