I was taken aback by this stoplight the other day. Fallen over, still functioning, and confusing everyone who saw it. You have to pay attention – green does not always mean go.

Green does not mean go for pregnant women either, in a different way. Ohhhhh yes, we’re going to talk about that green.

We don’t really know how many women use marijuana during pregnancy … probably anywhere from 3 to 34%. Different regions have higher (helloooo Colorado) or lower levels of use, and women may be hesitant to disclose their use so we can’t get a proper count.

But we see the trend. More and more states are making it legal to use marijuana, both medically and recreationally.  As of late 2015, 23 states have legalized the use of medical marijuana.  Four of these states – Alaska, Washington, Oregon, and Colorado- have also legalized use of recreational marijuana. California keeps trying but failing.

But how safe is it in pregnancy?

There are no absolute answers, but a recently published composite review (yes, marijuana is getting press from all sides) assessed information from hundreds and hundreds of studies. They looked at risks and benefits for women using marijuana during pregnancy

Below, the quick and dirty:

Potential benefit

Treatment of nausea and vomiting of pregnancy.

• We know marijuana helps minimize nausea and vomiting from chemotherapy for cancer patients, but can it help pregnant women with the same symptoms? For women who already use medical marijuana for other indications, yes, it helps alleviate nausea. But, women who use marijuana are also more likely to have severe pregnancy associated nausea and vomiting in the first place. So I guess that’s the old chicken and the egg question.
• No studies have used marijuana as a primary treatment option for women who weren’t already using it for other indications. Not sure if that study will ever be done in light of the risks I’ll highlight below … so … ultimate answer is  … effect is unknown.

 

Potential Risks

Increased risk of stillbirth

• Probably 2X the risk compared to women who don’t use marijuana. Many marijuana smokers also smoke cigarettes, which is a known risk factor for stillbirth as well, so the actual risk is unknown. But still, this is arguably the worst pregnancy outcome ever. Don’t increase your chance.

Neurodevelopment, behavior, and intelligence

• Studying neurodevelopment is so hard because of innumerable confounding issues. Genetics, development, socioeconomics, you name it. Schools, teachers, caretakers, whether your parents smoke. All of these can make a difference and there’s no way to isolate one issue and disregard the rest. But still, people have tried. And in the best study to date, if exposed to marijuana in utero, kids between the ages of 4 and 9 had poorer vision; worse learning and language comprehension; and attention, memory and behavior problems. There are definitely some concerning patterns.

Breastfeeding?

• Yes, marijuana, consumed in any way, reaches breast milk, at a rate of about 0.8% that of the mom’s exposure. That’s tiny but it’s not nothing. I think this correlates with the neurodevelopment issues above. Your baby’s delicate little brain is growing and expanding at a tremendous rate. Don’t limit it by exposing him to marijuana through breast milk. Marijuana use may also suppress amount of milk produced too, which may not be dangerous but can be frustrating.

Baby (fetal) growth restriction

• Many studies show a correlation between decreased fetal growth and maternal marijuana use. However, the reported growth difference is about ¼ of a pound and the effect of this is unknown (but I think pretty much negligible)

 

A few other considerations

Associated with preterm birth?. Some studies say yes, most say no. Consensus is no.

Congenital anomalies? Nope.

Anything else? In high doses, marijuana can slow heart rate and lower blood pressure. In moderation or low doses, it can increase heart rate. Some common medications given during labor can also increase heart rate or lower blood pressure, so these meds shouldn’t be given. It basically makes anesthesia more complicated and potentially more dangerous, but not always.

 

Overall, I say use the same precautions you would with any other medication – it’s not considered safe in pregnancy, so don’t use it. But if you must – use in moderation, take the lowest effective dose to control your symptoms, and tell your doctor so she can help optimize your and your baby’s health.

 

Source: Torri Metz and Elaine Stickrath. Marijuana use in pregnancy and lactation: a review of the evidence. AJOG Dec 2015 761-778