The Research

For more in depth information on Substance Abuse please click here

Affiliated with

Offord Centre for Child Studies

McMaster University - Health Sciences

McMaster Children's Hospital

Does prenatal exposure to cannabis effect the growth of unborn children? | Print |  E-mail
Behaviour and Mental Health Problems - Substance Abuse
In short…

This study showed that using Marijuana or hashish during pregnancy can cause serious growth and development problems in the unborn child.  It is best to quit using these substance before getting pregnant.

The Issue: Public health programs have alerted pregnant women to the dangers posed to their unborn children if they smoke tobacco or drink alcohol.  Both of these substance can have severe consequences, particularly because of their effects on growth and development of the unborn child.  However, there have been few attempts to warn against the use of marijuana and hashish during pregnancy.  There have been many animal studies that have shown the harm done by the active ingredient in marijuana and hashish, --cannabis -- but only few study have been done with humans.

The Research: This was a study of the offspring of 3 groups of women: those who stopped using cannabis before pregnancy, those who used it in early pregnancy, and those who used cannabis throughout pregnancy, compared to those who did not use cannabis during pregnancy. This study looked at growth patterns of unborn children of women who did or did not use marijuana while pregnant, and those who used marijuana and/or alcohol or tobacco at the same time to determine if marijuana had particular effects not associated with the other substances.  Of 8,800 women taking part in a study of early environmental and genetic determinants of growth, development, and health from the prenatal period onward, 7,452 mothers had acknowledged ever using cannabis,  alcohol and/or  tobacco. Ultrasound assessments of their unborn children in early, mid-, and late pregnancy determined the length of the thigh bone, the circumference of the abdomen and head, and the size of the cerebellum.  The multiple examinations carried out as part of usual prenatal care were used to determine if any effects were related to the timing of exposure to these substances. To determine the effects of cannabis alone, the data from the mothers using cannabis only were analyzed.

The Results: Of the participating mothers, 214 used cannabis when pregnant; 173 (81%) quit in early pregnancy. Forty-one (19%) continued using cannabis throughout their pregnancy and 85% of them also smoked tobacco.  The unborn children of mothers who used cannabis alone in early pregnancy or who continued to use it alone throughout pregnancy showed reduced head growth (associated with cognitive ability) and body weight.  The offspring of those who used cannabis throughout pregnancy showed more severe effects.

Conclusions: The growth and development of the offspring of women who use cannabis during pregnancy is hampered, with the potential to lead to learning difficulties and physical health problems.  Quitting cannabis use prior to conception is advised as the best way to prevent these serious problems.

+++

The preceding is a summary of: el Marroun H., Tiemeier, H., Steegers, E.A.P., Jaddoe, V.W.V., Hofman, A., Verhulst, F.C., van den Brink, W., Huizink, A.C. Intrauterine cannabis exposure affects fetal growth trajectories: The Generation R Study. 2009;. 48(12): 1173-1181

Attachments:
FileFile sizeLast Modified
Download this file (Prenatal exposure.pdf)Prenatal exposure to cannabis109 Kb09/02/10 11:31
Last Updated on Tuesday, 09 February 2010 11:32