Marijuana during pregnancy: is it safe?

It’s hard to imagine there will ever actually be enough research on the effects of drugs during pregnancy, because no one wants to take the risk of testing something that could cause potential problems. Still, it’s strange to think of how little conclusive research there is on the pregnancy-effects of the most commonly used illicit drug.

Official recommendations, like that of the American College of Obstetricians and Gynecologists, advises against marijuana use, either by smoking or by ingesting it, during pregnancy and lactation. This recommendation isn’t based on evidence that it is definitevely unsafe though, but rather the absence of evidence that it is safe. In fact, the evidence that does exist is frustratingly contradictory.

For one thing, most researchers find it difficult to control for use of alcohol, cigarettes, or illicit drugs when analyzing results. It’s not like scientists can set up a blind study where they assign some pregnant women to use marijuana and some to not, so they depend on the way people report on the things they’re already doing. This means it can be hard to separate out the effects of the one thing they want to test from the other factors affecting fetal health and development. It also means that, because marijuana use is a criminal offense in many states and countries, and is often frowned upon to varying degrees in other places, legally or otherwise, there is a good chance that use is underreported in the data used for studies. 

The evidence that exists now does not suggest a connection with birth defects or childhood cancer, though both have been suggested at different points. Instead, of the three major studies often used as evidence in the debate over marijuana use during pregnancy, two draw connections between differences in behavior, memory, and reasoning in children 3 years and older who were exposed to marijuana in the womb, while the third, a study of Jamaican women, some of whom smoked a significant amount during pregnancy, showed no negative effects on the children exposed in the womb.

Between the three studies, it’s generally agreed in the medical community that not enough research has been done to make a true recommendation. However, in the absence of much evidence supporting its use, it’s almost certainly best to hold off during pregnancy. If you do have any questions about marijuana during pregnancy, it’s a good idea to speak with your healthcare provider.

  • “Marijuana and pregnancy.” March of Dimes. March of Dimes Foundation. January 2017. Web.
  • van Gelder, Marleen M. H. J.; Donders, A. Rogier T.; Devine, Owen; Roeleveld, Nel; Reefhuis, Jennita. “Using Bayesian Models to Assess the Effects of Under-reporting of Cannabis Use on the Association with Birth Defects, National Birth Defects Prevention Study, 1997–2005.” National Birth Defects Prevention Study. Paediatric and Perinatal Epidemiology. August 26, 2014. Web.
  • Linn, S.; Schoenbaum, S.C.; Monson, R.R.; Rosner, R.; Stubblefield, P.C.; Ryan, K.J. “The association of marijuana use with outcome of pregnancy.” American Journal of Public Health. Alpha Publications. October 1983. Web.
  • Tortoriello, G. et al. “Miswiring the brain: Δ9-tetrahydrocannabinol disrupts cortical development by inducing an SCG10/stathmin-2 degradation pathway.” PubMed. U.S. National Library of Medicine. January 27, 2014. Web.
  • Committee on Obstetric Practice. “Marijuana use During Pregnancy and Lactation.” The American College of Obstetricians and Gynecologists. The American College of Obstetricians and Gynecologists. July 2015. Web.
  • Hayes, J.S.; Lampart, R.; Dreher, M.C.; Morgan, L. “Five-year follow-up of rural Jamaican children whose mothers used marijuana during pregnancy.” PubMed. U.S. National Library of Medicine. September 1991. Web.
  • Jaques, S.C. et al. “Cannabis, the pregnant woman and her child: weeding out the myths.” Journal of Perinatology. Nature America, Inc. January 23, 2014. 
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