Study shows pot, pregnancy don’t mix

Smoking marijuana during pregnancy may be more dangerous than you think, according to the latest research from Cincinnati Children’s.

A study led by Sudhansu K. Dey, PhD, director of the Division of Reproductive Science at Cincinnati Children’s, and his colleagues reports that pregnant mice have trouble forming healthy placentas if they have abnormal levels of marijuana-like compounds called endocannabinoids in their systems. This in turn may lead to a dangerous condition called preeclampsia, a form of high blood pressure during pregnancy that can require premature delivery to protect the mother’s life.

Dey’s findings add to a growing body of evidence that marijuana use can disrupt pregnancy, leading to higher rates of ectopic pregnancies, miscarriages and premature birth.

The latest research involved two lines of genetically engineered mice. One line was bred to produce excessive levels of endocannabinoids, the other to lack the receptors for the compounds. In both extremes, out-of-balance endocannabinoid signaling disrupted pregnancy. Full details of the findings were recently published in the Journal of Biological Chemistry.

To most people, it may seem obvious that smoking marijuana during pregnancy is a bad idea – much like drinking alcohol or smoking cigarettes. But some people believe marijuana is a virtually harmless drug that even offers beneficial health effects in some situations.

So what should women of child-bearing age make of these latest findings? We asked Dey’s research team to help explain.

Should pregnant women avoid marijuana use?

Yes. Unbalanced endocannabinoid levels may affect pregnancy in several ways including pre-implantation embryo development, embryo transport in the fallopian tubes (a signature of ectopic pregnancy), and placenta formation. There is anecdotal evidence that women smoking marijuana have had ectopic pregnancies. Our recent studies suggest that marijuana use also compromises embryo development later in pregnancy.

What if a woman smoked some pot back in high school or college, but doesn’t anymore? If she gets pregnant, is her baby at risk?

There is no report suggesting adverse effects lasting more than half a year after stopping marijuana smoking. If you are a regular marijuana user, it is advisable to stop using and wait at least three months before attempting to conceive.

If a woman discovers she became pregnant while still smoking pot, is there anything she can do to reduce the risks? Or has the damage been done?

Once you know that you are pregnant, stop using marijuana and let your body correct its own cannabinoid balance. It is almost impossible to use medications to accomplish this without going too far in the other direction. Excessively high cannabinoid signaling can harm a pregnancy, but so can excessively low signaling.

Does it matter if the male partner smokes marijuana? Or is this finding strictly related to female consumption?

This study focused on the effects of female consumption. However, other studies in males suggest that marijuana use compromises sperm mobility and fertility.

Why do these studies use mice? Why can’t this information be collected directly from humans?

It would be illegal and unethical to conduct studies that expose pregnant women – and their fetuses – to marijuana.  When attempting to conduct retrospective studies – looking at the pregnancy outcomes of women who did smoke pot — it can be extremely difficult to get accurate information about the extent of the marijuana use. This is why research in this field has been confined to studies in animal models such as mice, which are used in the laboratory to try and mimic human exposures and outcomes.

What impact should these findings have on the rising popularity of medical marijuana and states acting to decriminalize the drug?

While marijuana may have some medical benefits, the drug also may compromise normal pregnancy outcome. Public health leaders need to fully consider the beneficial versus adverse effects as they debate the medical marijuana issue. Down the road, it may be possible to develop marijuana-like compounds without the adverse effects of marijuana.

Tim Bonfield

About the Author: Tim Bonfield

Tim Bonfield is an associate in Marketing & Communications at Cincinnati Children's. He joined the medical center in 2009 after 17 years at the Cincinnati Enquirer as an award-winning health beat writer, assistant local news editor and Butler-Warren bureau chief. Tim is a proud Cincinnati native and the frazzled father of two teen daughters.

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