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USDTL Research

Marijuana Use in Pregnancy

By Bob Demaree, Clinical Projects Manager, USDTL

Marijuana is the illicit drug most often used by women during pregnancy. The 2010 National Survey on Drug Use and Health reported that 4.4 % of women used illicit drugs at some point during pregnancy; marijuana was the primary drug of abuse for this group. Reported marijuana use in the study increased by more than 20 percent in the years2007-2010.1

While considered a benign substance by many people, an increasing number of studies have identified potential adverse effects during pregnancy. Human and animal studies have identified issues with brain development and cognitive function. Marijuana use in pregnancy has been associated with low birth weight, prematurity, shorter birth length and an increased likelihood of admission to the NICU.2 Other studies have reported negative long term outcomes including poor performance on intelligence tests, issues with hyperactivity, attention, and impulsivity.3

Marijuana is often used in combination with other substances, primarily tobacco and alcohol. In a 2008 study, Rivkin et al. reported that exposure to cocaine, alcohol, marijuana and tobacco, either alone or in combination, may effect brain structure. A group of 35 young adolescents with confirmed prenatal drug exposure were tested by volumetric MRI. The subjects exhibited reductions in gray matter and total brain volume. The study found that exposure to any of the individual substances had an adverse effect, the effect increased with combined exposure.4

Delta- 9-tetrahydrocannabinol (THC), the psychoactive component in marijuana, is known to pass through the placenta. The level of THC in current marijuana is up to 20 times greater than marijuana produced in the 1970’s.5 THC acts as a partial agonist at the CB-1 cannabinoid receptor sites located primarily in the central nervous system and the CB-2 receptors located in the immune system. The THC levels in high potency marijuana may disrupt normal development.6

Synthetic marijuana products like Spice and K2 were introduced into the market in 2008. The synthetic cannabinoid agonists in these new products are 500-600 times more potent than THC found in plant-based material.6 While the structures of the synthetic materials are different than THC these new cannabinoids act as agonists at the CB-1 receptor site. The JWH-018 cannabinoid has full agonist properties whereas THC is only a partial agonist. Users are often surprised that the full agonist effects are not the pleasant experience of native THC. 7 Routine drug test methods will not identify synthetic drugs.

United States Drug Testing Laboratories, Inc. (USDTL) has been involved in monitoring various forms of drug and alcohol abuse since 1991. Currently each newborn test panel for the meconium, umbilical cord and breast milk sample matrices offers assays to identify marijuana exposure. At this time USDTL offers synthetic marijuana testing in urine samples only. New assays could be introduced if interest grows in testing newborns for the synthetic cannabinoids.


  1. Substance Abuse and Mental Health Services Administration, Results from the 2010 National Survey on Drug Use and Health: Summary of National Findings, NSDUH Series H-41, HHS Publication No. (SMA) 11-4658. Rockville, MD: Substance Abuse and Mental Health Services Administration, 2011.
  2. Hayatbakhsh MR, Flenady VJ, Gibbons KS, Kingsbury AM, Hurrion E, Mamun AA, Najman JM. Birth Outcomes Associated with Cannabis use Before and During Pregnancy. Pediatr Res. 2012 Feb;71(2):215-9. doi: 10.1038/ pr.2011.25. Epub 2011 Dec 21.
  3. Gray TR, Eiden RD, Leonard KE, Connors GJ, Shisler S, Huestis MA. Identifying Prenatal Cannabis Exposure and Effects of Concurrent Tobacco Exposure on Neonatal Growth. Clin Chem. 2010 September; 56(9): 1442-1450. Doi: 10.1373/clinchem.2010.147876.
  4. Rivkin MJ, Davis PE, Lemaster JL, Cabral HJ, Warfield SK, Mulkern RV, et al. Volumetric MRI Study of Brain in Children with Intrauterine Exposure to Cocaine, Alcohol, Tobacco, and Marijuana. Pediatrics. 2008 April;121 (4) 741-750.
  5. Potter DJ, Clark P, Brown MB. Potency of Delta 9-THC and Other Cannabinoids in Cannabis in England in 2005: Implications for Psychoactivity and Pharmacology. J Forensic Science. 2008 Jan; 53 (1)90-94.
  6. Pychoyos D, Yaragudri VK, Spice ‘Herbal High’, and Early Neural Development: Implications for Rescheduling and Legalization. Drug Test Analysis.doi =: 10.1002/dta. 1390.
  7. Cheng S, Yeo J, Brown E, Regan A. Bath Salts an Synthetic Cannabinoids: A Review 7.31.2012.

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