SUMMARY:

The US Surgeon General released an advisory regarding marijuana use during pregnancy and the potential for adverse outcomes. This advisory echoes concerns of ACOG and AAP regarding potency and potential harms during pregnancy and adolescence. Use in pregnancy has doubled (3.4 to 7%) and appears to be associated with adverse outcomes including LBW. ACOG’s updated committee opinion on marijuana use in pregnancy and lactation, due to reported association between marijuana use and impaired neurodevelopment in the offspring, recommends that the use of marijuana in the pre-conception, pregnancy, or lactation periods should be discouraged.

KEY POINTS:

Background 

• Prevalence of marijuana use (self-reported) during pregnancy: 2-5% 
  • May be as high as 28% in young, urban and disadvantaged populations 
•  Up to 60% of women using marijuana may continue use during pregnancy  
  • Data suggests that women are not aware of risks and consider marijuana to be cheaper and safer than tobacco

Pharmacology 

• Tetrahydrocannabinol (THC) is the active substance  
  • Distributed rapidly to the brain and fat 
  • Metabolized by the liver 
  • Half-life:  20-36 hours in occasional users and may be up to 4 to 5 days in heavy users 
  • Excretion: Up to 30 days 
• Fetal THC levels are
  • Approximately 10% of maternal levels (animal models)
  • Found in breast milk (human studies)

Perinatal Risks and Outcomes  

CNS Effects Including Visual and Behavioral Outcomes 

• Cannabinoid receptors have been detected in humans as early as 14 weeks gestation and endocannabinoids may be important for neurodevelopment
• Animal models suggest that exogenous cannabinoids may interfere with normal brain development
• Children exposed to prenatal marijuana may have
  • Lower scores on tests of visual problem solving
  • Visual-motor coordination
  • Decreased attention span
  • Behavioral problems 

Structural malformations 

• Available evidence does not suggest increased risk for fetal structural malformations 

Perinatal death 

• Marijuana use does not increase risk of perinatal death
  • Relative risk (RR) 1.09; 95% CI, 0.62 to 1.91
• Some studies have shown higher risk of stillbirth but may be confounded by cigarette smoking and other factors
  • RR 1.74; 95% CI, 1.03 to 2.93

Birth weight 

• Some studies have shown an association between marijuana use and lower birth weight (<10th percentile) even after adjusting for tobacco use
• A meta-analysis with primary outcome of birth weight <2,500 did not show a difference when adjusted for other factors, such as tobacco use, but did identify possible effects when data was stratified by
  • Weekly users
  • Use in the 1st and 2nd trimesters 

Preterm birth

• A meta-analysis with primary outcome of preterm delivery <37 weeks did not a show a relationship when adjusted for tobacco use
  • Possibility exists that tobacco “may be an important mediator for some “adverse pregnancy outcomes”

Note: For perinatal death/stillbirth, birthweight and preterm birth, data derived from meta-analysis (see ‘Learn More – Primary Sources below) and other more recent studies

Breastfeeding 

• There are insufficient data on the effects of marijuana use on breastfeeding infants 
• Bertrand et al. (Pediatrics, 2018) identified significant transfer of cannabinoids into breast milk following marijuana us (see ‘Related ObG Topics’, below)
• At this time, both ACOG and AAP recommend that marijuana use during lactation should be discouraged

Medical Marijuana Use 

• The FDA does not evaluate nor regulate medical marijuana use 
• There are currently no indications for use in pregnancy 
• ACOG recommends the following
  • Encourage women to discontinue marijuana use
  • Avoid prescribing or suggesting the use of marijuana for medicinal purposes during pre-conception, pregnancy, or lactation periods 
  • Identify alternative therapies with better safety profiles

Other Counseling Notes

• All pregnant women, or those planning to become pregnant should be asked about their use of alcohol, tobacco, and drugs including marijuana
• Discuss potential adverse events
  • More research is necessary to determine whether marijuana is an isolated risk factor for adverse outcomes or whether findings are a result of confounding related to other factors (e.g., tobacco use, other substances, socioeconomic factors, nutrition) or recall bias
• ACOG recommends that patients should be made aware that screening for substance use allows for the provision of treatment when necessary and not to punish
• In addition, the ACOG guideline states

…patients should also be informed of the potential ramifications of a positive screen result, including any mandatory reporting requirements

Seeking obstetric–gynecologic care should not expose a woman to criminal or civil penalties for marijuana use, such as incarceration, involuntary commitment, loss of custody of her children, or loss of housing

Learn More – Primary Sources:

ACOG Committee Opinion 722: Marijuana use in pregnancy

ACOG Breastfeeding Page

AAP: Marijuana Use During Pregnancy and Breastfeeding – Implications for Neonatal and Childhood Outcomes

Maternal Marijuana Use and Adverse Neonatal Outcomes: A Systematic Review and Meta-analysis

U.S. Surgeon General’s Advisory: Marijuana Use and the Developing Brain

Related ObG Topics:

Does Marijuana Affect Time to Pregnancy?

Marijuana Detection in Breast Milk: Does Route and Timing Make a Difference?