By Sonia Alvarado, MotherToBaby California Teratogen Information Specialist

I wrote a blog about marijuana and pregnancy three years ago and it’s become the most visited blog on the MotherToBaby website. No surprise, considering that marijuana is an even hotter topic today than it was previously! Three years ago, two states had laws allowing recreational use. Now, 29 states allow medicinal use, recreational use or both (with limits on amounts varying from state to state). I was recently asked to revisit this topic and to provide an update on what we know about marijuana use during pregnancy and breastfeeding.

In this blog article, I use the terms marijuana, cannabis or pot interchangeably, as do most people.

At this time, there is no FDA approved indication for cannabis use as a medical treatment. The FDA gives approval to drugs only when the manufacturers of those drugs have gone through all of the required testing, have met the standards for safety, and have shown that it works when treating specifically named conditions. Marijuana has not met these standards. However, there are two FDA-approved drugs that contain man-made (synthetic) forms of marijuana. These medications, dronabinol and nabilone, are used to treat nausea caused by cancer medications. Neither one has been studied in human pregnancy, so we do not know how safe they are if taken during pregnancy.

The use of marijuana by pregnant women, either unintentionally before they know that they are pregnant or intentional use after pregnancy recognition, continues to increase. One survey suggests that marijuana is the leading recreational drug that pregnant women report using. The National Survey of Drug Use and Health reported that 3.85% of pregnant women reported using marijuana in the past month in 2014, compared with 2.37% in 2002. Other self-report studies indicate the number may be 5-8%. Our information service also receives many questions from pregnant and breastfeeding women who want to continue to use marijuana. Because of increasing legalization, the reported increased use and the need for answers from the public and health care providers, MotherToBaby has set aside sections of its June 2017 professional meeting in Denver, Colorado to bring experts together to discuss the latest research.

What do pregnant women, doctors and teratogen specialists, like myself, want to know about cannabis use during pregnancy?

  • We know that the developing baby is exposed to drugs, medications, infections and chemicals in the mother’s blood. Pregnant women, their health care providers and researchers want to know the differences in the amounts of the drug that reach the blood when cannabis products are used topically, when they are ingested and when they are smoked.
  • We also want to know the risks associated with each type of exposure and the doses that are associated with the risk. For example, what is the difference in risk if a pregnant woman smokes pot once a day (a hit or two or more) vs. smoking pot once a week (one hit or two)? What about if she ingests the drug? What is the difference in risk to her developing baby?

It used to be that teratogen specialists like me were mostly concerned about the risk for birth defects, such as cleft lip and palate, or heart defects. However, now we know that for some drugs, the risks are not specific just to the baby’s structure, such as development of limbs. Instead, some drugs, like alcohol, affect development of the baby’s brain and therefore the effects on the child’s learning and behavior might not be noticed until much later. We need studies that follow children exposed prenatally to marijuana, in all its forms and at a range of doses, so that we can better inform pregnant women if their babies have risks for learning or mental health problems.

What the Available Studies Do Show
The few studies that have focused on birth defects like heart defects or cleft lip and palate have not found a specific pattern of birth defects linked with marijuana when it is smoked. This does not mean that we know for sure that the drug does not ever cause birth defects. What it could mean is that the risk may be small or there is an increased risk only at higher doses or more frequent use. Larger and better studies are needed to determine if there is or is not an increased risk. We do not know for sure yet, and studies are continuing.

Many of the studies have continued to report a higher risk for low birth weight babies, preterm delivery, babies that are small for gestational age and higher rates of admission to intensive care nurseries for babies born to women who smoke marijuana during pregnancy. All of these complications are important and associated with serious health risks for the newborn baby. They could require a longer hospital stay, medical treatment and in some cases, could result in life-long disability. Prematurity, regardless of the cause, is associated with a higher risk for apnea, bleeding in the brain, lung problems (breathing problems), intestinal problems, a higher risk for infections and other problems. Studies continue to look at the issue of complications from smoking pot during pregnancy.

THC and Baby’s Brain
Another issue that is very important is the risk of learning and mental health problems from prenatal exposure to cannabis. As many people know, the primary psychoactive component of cannabis is Δ9-tetrahydrocannabinol or THC. This part of the plant produces the “high” when it binds to cannabinoid receptors in the brain. In the field of psychiatry, for some time it has been reported that smoking pot is linked to psychosis or schizophrenia. This type of research has generated questions about the risk to the unborn baby’s brain from exposure to the drug. Because the brain of the baby continues to grow after birth, there is also concern about what can happen if the baby is exposed to THC through breastmilk. This is part of the important research that will be presented at the MotherToBaby/OTIS conference in Denver this month. We look forward to hearing what the researchers have been learning about cannabis in pregnancy and lactation. Let’s just say I have a strong feeling that after this meeting and as we get more and more up-to-date, evidence-based information for our readers, marijuana blog #3 will be right around the corner!

Sonia Alvarado is a bilingual (Spanish/English) Senior Teratogen Information Specialist at MotherToBaby’s California affiliate. MotherToBaby aims to educate women about medications and more during pregnancy and breastfeeding. Along with answering women’s and health professionals’ questions regarding exposures during pregnancy/breastfeeding via MotherToBaby’s toll-free helpline, email and private chat counseling service, Alvarado has provided educational talks regarding pregnancy health in community clinics and high schools over the past decade.

MotherToBaby is a service of the Organization of Teratology Information Specialists (OTIS), suggested resources by many agencies including the Centers for Disease Control and Prevention (CDC). If you have questions about exposures during pregnancy and breastfeeding, please call MotherToBaby toll-FREE at 866-626-6847 or try out MotherToBaby’s new text information service by texting questions to (855) 999-3525. You can also visit MotherToBaby.org to browse a library of fact sheets about dozens of viruses, medications, vaccines, alcohol, diseases, or other exposures during pregnancy and breastfeeding or connect with all of our resources by downloading the new MotherToBaby free app, available on Android and iOS markets.