In mid-December of 2019, The American Journal of Case Reports published an article documenting a case of sudden infant death. What makes this tragic report remarkable is the identification of the mother’s marijuana use while pregnant as the cause of death. This is an extraordinary claim. There have been no credible reports of adult or childhood deaths due to cannabis. Similarly, there has never been a case of terminated pregnancy or stillbirth due to a mother’s marijuana use. This report comes at a time when rates of cannabis use among pregnant women is on the rise. Is this a sign of things to come, or yet another example of coroners jumping to the wrong conclusion?
The report tells the story of an 11-day old infant found lying face up and unresponsive at home in Illinois. Upon discovery, the child was brought to the hospital, where she was pronounced dead. The child had been born at 36.5 weeks gestational age, which is a little early, but according to the case report she was “relatively healthy” on delivery. The autopsy revealed no signs of suffocation or trauma, no broken bones, no signs of infection, no genetic abnormalities, and no drugs or toxins in the child’s blood.
The cause of death was internal bleeding due to hemorrhaging of the liver, adrenal glands, and thymus. Microscopic analysis revealed regions of necrosis (dead tissue) in each of these organs. A toxicology screen on the umbilical cord detected elevated levels of THC metabolites, proof that the mother had used cannabis within the last trimester. Based on this information, the coroners concluded that the internal bleeding was caused by the mother’s marijuana use.
A Horse of a Different Color
The case for internal bleeding seems incontrovertible (though it should be noted that I’m not a forensic pathologist and therefore am not qualified to have a professional opinion on the matter). Where I get hung up is this claim that marijuana caused the organ damage. Part of my skepticism comes from the fact that this is a diagnosis of exclusion. This is a fancy way of saying, “We’ve ruled out all possibilities except one.” There’s nothing wrong with this approach; in fact, the scientific method is based on it. The problem is that there’s no way to know if you’ve tested every possibility.
Let me give you an example. Doctors-in-training are often told some version of the following: “When you hear hoofbeats, think of horses, not zebras”. While this is meant to guard against diagnosing rare conditions without sufficient evidence, I think we can also apply it to the diagnosis of exclusion. Suppose we hear some approaching hooves. Curious, we look to see if the animal has black and white stripes, and find that it does not. Therefore, it must be a horse! Or is it…
In essence, the authors of this paper are trying to convince us that they’ve discovered a hoofed animal the world has never seen before. Not only are they claiming to have uncovered the first case of death by marijuana ingestion, they’re claiming that a mother’s marijuana use while pregnant caused the death of an otherwise healthy child after it was born. I’m not saying they’re wrong. I’m not saying they can’t be right. But in order to believe this, I need a lot more than, “There are no other explanations.”
The authors must have anticipated this objection, because they made sure to address it head on. According to them, “[t]his case is unique in that other possible causes of death can be eliminated.” What they mean is that all other causes can be ruled out, but strictly speaking, this is impossible. The author’s refusal to acknowledge this fact makes me more skeptical of their conclusion, not less, especially when there are plausible alternatives not addressed in the report.
For example, the most common cause of adrenal hemorrhage in infants is hypoxia (lack of oxygen) due to complications during birth. Adrenal hemorrhages usually occur within the first few weeks of life, as happened in this case. Though the authors attest to the apparent health of the child, they mention nothing about potential difficulties during birth. Remember, too, that the child was born slightly pre-term, which is associated with maternal cannabis use. Now, it may be that everything went smoothly, and this explanation can be safely excluded. But if I were writing this report and wanted to be taken seriously, I would make damn sure that I addressed the most common cause of a major symptom in as much detail as possible. This glaring omission does not inspire confidence in the authors.
Another likely cause is an undetected genetic condition. Specifically, the involvement of three highly vascularized organs points to a bleeding disorder. The report says they did genetic testing, but once again we’re left short of details. Which conditions are consistent with their findings? Were those the ones that were tested for? It’s never made clear. Further, a negative test does not mean that it isn’t a genetic disorder. It only means that it wasn’t detected. This may seem like quibbling, but it’s an important distinction. False negative results do happen. Also, genetic tests only screen for conditions we know about. This could be a rare disorder with no known cause, or a common disorder with a unique presentation, leading the doctors to test for the wrong thing. I know this from firsthand experience, since I used to work on a rare genetic disorder, NGLY1 Deficiency, as an academic researcher. If you’ve got a few minutes, I highly suggest watching this video to learn more:
Of course, this is just speculation. And because of my research experience, I’m definitely biased toward the rare disorder hypothesis. I could be totally wrong, and they did everything correctly. But as it stands, there are other reasonable explanations that can’t be excluded based on what’s in the report.
Lack of Positive Evidence
Now, all this wouldn’t matter if there was strong evidence in favor of their conclusion. For example, if it was well known that marijuana caused internal organ damage, there would be less cause for skepticism. But if that evidence exists, I haven’t seen it, and apparently neither have the authors of this case report.
The one bit of evidence they marshal in favor of their conclusion is an animal study from 1987. In that work, researchers administered intravenous THC to pregnant rhesus monkeys, and then tested various fetal organs for the presence of THC. They found that it accumulated in the fetal adrenal glands, thymus, and liver, the same organs affected in the deceased infant. This paper also demonstrates that THC can cross the placental barrier and show up in the fetus.
In rhesus monkeys.
This is hardly enough evidence to draw such a stark conclusion about maternal cannabis use. True, the organs affected were the same. But there was no evidence of damage to those organs in the monkeys, or at least it wasn’t mentioned. Further, no THC was detected in the infant’s blood. I find it a bit hard to believe that the child was dosed with so much THC that it caused her organs to burst, but it was undetectable on a toxicology report. There’s a possibility that it was undetectable in the blood because it had been absorbed by those organs. But then why didn’t they test pieces of the organ tissue directly?
Not Ruled Out, Not Ruled In
Again, I’m not saying that the authors of this case report are wrong, or that what they say happened is impossible. They could very well be right. And it’s probably a good idea for women to reduce or avoid marijuana use while pregnant, just as it’s a good idea to avoid smoking, drinking, caffeine, etc. This is especially true if cannabis is illegal in your state, as it may be tainted with pesticides, heavy metals, or other toxins that are known to cause liver damage and organ failure.
That said, I’m inclined to reject the conclusions of this case report. The evidence in support of the claim is weak and circumstantial, and there are plausible alternative explanations that haven’t been satisfactorily ruled out. Extraordinary claims require extraordinary evidence. In this case, the evidence isn’t even ordinary.
About the author:
J. Brandon Lowry holds a PhD from the Institute of Molecular Biology at the University of Oregon. A digital nomad and freelance writer, he writes about cannabis, science, health, and travel. He is also editor at Midnight Mosaic Fiction.