(Photo: Wikimedia Commons)

(Photo: Wikimedia Commons)

Experts are still unsure of the risks associated with using marijuana during pregnancy.

It’s widely known that pregnant women should abstain from drinking alcohol and smoking cigarettes because those substances can harm their growing baby. But what about marijuana?

The question of marijuana’s safety during pregnancy has been studied since the 1960s among fears that it would cause birth defects. And over the years, a number of birth-related problems seem to have been identified.

“There have been studies that suggest cannabis use in pregnancy may be linked with lower birth weight and premature birth, and with subsequent behaviour issues in the children,” explains Dr. Arnold Shoichet, a physician who also serves as a board member for the Medicinal Cannabis Resource Centre, a cannabis clinic based in Vancouver, BC.

On the other hand, much of these findings are weak in nature. In fact, whether there are truly any negative effects of using marijuana during pregnancy remains a mystery.

“Critics point out some of these studies have ambivalent results,” notes Dr. Schoichet. “A cause-effect relationship between the measured outcomes and cannabis use has not been established.”

Problems with Studies

Though there have been many studies done on the effects of marijuana on a developing fetus, most health professionals would agree with Dr. Shoichet that the area is not studied well enough, and there are problems with the studies that have been done.

In fact, many of the studies rely on the pregnant mother to self-report how much marijuana they have been using, and this is not always the most accurate way of collecting data. They might have forgotten how much they really used, or they might under-report their usage for personal reasons. Those problems are always present with studies that rely on self-reporting.

And while you might be hard-pressed to find a doctor or scientist who would tell you that it’s safe to use cannabis during pregnancy, there have been a small number of studies which seem to indicate that it might be.

Jamaican Study

One study conducted by Dr. Melanie Dreher looked at pregnant mothers in Jamaica before and after pregnancy. Dr. Dreher was the dean of nursing at Rush Medical Center in Chicago when she did the study. Today she’s retired and works as independent consultant, and is also a member of the Chicago Board of Health.

Dr. Dreher’s study was published in The American Journal of Pediatrics in 1994. She studied mothers in rural Jamaica, some who were using cannabis to remedy their morning sickness, and others who weren’t using it at all. After the babies were born she used the Neonatal Assessment Scale at 3 days, and again at 1 month, to measure the babies’ neurological performance and behavior.

Dr. Dreher expected to find complications like low birth weight or compromised neurological development, but surprisingly none of those things were found. On the contrary, the babies who were born to mothers that used marijuana during pregnancy showed better social skills than the babies who were born to mothers that didn’t use cannabis.

But Dr. Dreher is quick to point out that these improvements are not attributed to the biochemical action of marijuana. Instead, she believes the different outcomes were more likely due to how the babies were raised.

Over the phone she explains, “[We] attribute it to rather the social differences between the marijuana-using mothers and the non-using mothers. Even though they were the same, they were matched for age and socioeconomic status, but there were differences in the lifestyles of the ingesting and non-ingesting mothers that we believe accounted for the differences. For example, many of the using mothers also were vendors of ganja and so they were pretty much at home most of the time in that neonatal period, so they were quite attentive to their babies.”

Dreher is quick to add that this is not meant to be an endorsement for the use of marijuana to have healthier babies, but it does demonstrate that, in this particular study, there are no adverse effects. She also did a longitudinal study with the same babies when they were four years old. The results, again, were fascinating.

“Again we found the performance of the children wasn’t correlated in any way with the neonatal exposure to cannabis,” says Dreher. “We would have done another study but the National Institute of Health really was not interested in funding a study that did not show something negative about marijuana.” Dreher regrets this denial to continue her study as a missed opportunity.

The Safest Best: Avoid All Substances

But the results of a single study shouldn’t be taken as evidence that marijuana is safe during pregnancy. The scientific community demands more than that. Generally speaking, for pregnant women the safest bet is to just avoid intoxicating substances altogether and this is what your doctor would probably advise.

“I think the best thing is to not use any substances, or medications, or drugs period, so the fetus has the best chance of development,” says Dr. Ilan Nachim, a Toronto-based physician who has prescribed medical marijuana to some of his patients. “With marijuana there have been studies done in terms of neurodevelopment sites in embryos, and I believe it’s mostly animals, but that is some of the evidence that we have that it shouldn’t be used.”

Some of those <a href="http://www.ncbi.nlm viagra pfizer france.nih.gov/pubmed/19572160″>animal studies are thought to be irrelevant to humans, because human embryos can behave differently. For example, one study into the effects of THC on primate fetuses showed degraded neurological development, but if that same study were done in humans the fetuses might react differently, so the validity of its findings with regards to humans is questionable.

Still, according to Dr. Nachim, if a pregnant woman is using marijuana for medical reasons, she should look for alternatives. “Ideally she shouldn’t use any medication. But if she has to, she should use medications that have more evidence for safety of the baby,” he concludes.