There is a lot of controversy surrounding cannabis use during pregnancy. While some argue smoking weed while pregnant has no negative effect and have healthy kids to prove it, others insist on a range of potential negative side effects, like low birth weight and decreased executive functioning. To try and figure out the truth behind marijuana and pregnancy, we looked at the studies, the laws, and spoke with a registered nurse 

Studies of Smoking Weed while Pregnant: Marijuana and Pregnancy

Even though medical and recreational use cannabis is legal throughout the U.S. and Canada, there are shockingly few scientific studies exploring the effects of cannabis use during pregnancy. To make matters more complicated, the studies that have been done concluded conflicting results.

Jessie Gill, a registered nurse and Founder of Marijuana Mommy tells Herb that a 2016 review published in Obstetrics & Gynecology found that cannabis didn’t have any adverse effects. This run contra to past studies, which have shown that cannabinoids, like THC, cross into the placenta entering the fetal bloodstream. “We don’t know if this exposure is harmful, however.” says Gill. She points us to another study conducted in the early ’90s which showed that cannabis might actually be beneficial when used during pregnancy. “Basically,” Gill offers, “we just don’t know.” 

The study, which looked at women in Jamaica who used cannabis during pregnancy and their children at different times in their lives, had promising results. They found that there was no significant difference in development between the cannabis using mothers and non-users’ children. In fact, at 30 days old, the babies of cannabis using mothers had better scores on autonomic stability and reflex tests.

Are There Any Benefits of Smoking Weed While Pregnant?

The most common reason women use cannabis during pregnancy is to help them deal with the nausea of morning sickness. Inhaled cannabis can provide nausea relief almost instantly, making it a popular addition to the treatment plans of those undergoing chemotherapy. As for pregnant women, the pharmaceuticals they are prescribed for morning sickness can also come with potential negative side effects to the fetus, like cleft lip, so cannabis can look like a safer alternative.

Gill points out that some women use cannabis during pregnancy to avoid taking other prescription meds that could potentially be more harmful to the baby, like opiates for pain, or benzos like Klonopin for anxiety. Gill also says medical cannabis can help women treat hyperemesis gravidarum, which is a severe nausea and vomiting condition during pregnancy, another reason pregnant women are turning to the herb despite insubstantial research on the subject.

“There are risks to everything we do,” says Gill. “Like all possible risks – caffeine, sushi, hair dye, etc. – every individual needs to do a personal cost/benefit analysis to see if it’s right for them.”

What are the Potential Risks of Smoking Weed While Pregnant?

The American Academy of Pediatrics warns mothers against smoking weed while pregnant because it could “place the fetus at risk.” That’s because some studies have shown negative effects of mother’s using cannabis while pregnant. While none of them are conclusive, let’s take a look so you can weigh the risks for yourself.

Many articles online claim that your baby could potentially have a lower birth weight if you use cannabis during pregnancy, which presents its own set of risks. This idea comes from a 2012 study conducted in Australia. The study found that babies born to mothers who used cannabis were 375 grams lighter than new mothers who abstained. The same study concluded that women who smoke weed while pregnant also risk preterm birth.

A 2015 review looked at past research of cannabis use during pregnancy and found that it could be linked to neurodevelopment issues in children like hyperactivity and poor cognitive function. However, this research is not conclusive and more studies are desperately needed before we can draw definitive conclusions.

At the same time, other studies have found no apparent adverse effects, dating back for decades. Like this 1982 study that followed 756 women over the course of their pregnancy. Of that group, 34% were marijuana users. The study found no developmental differences in infants of mothers who consumed marijuana during pregnancy and breastfeeding.

Smoking Pot While Pregnant: Marijuana and Pregnancy Laws

Despite the lack of evidence that smoking weed while pregnant can harm the baby, new and expecting mothers are still being visited by Child Protective Services (CPS) for testing positive for THC. Because cannabis is still federally a Schedule I substance in the U.S., meaning a drug with no medical use and high potential abuse, it’s still illegal for parents to smoke weed. Unfortunately, the same is true even if parents are medical cannabis patients or live in a legal adult use state, like California. There are horror stories of parents losing custody of their children because of cannabis use in the home and positive THC test results.

What’s more, some states have laws against cannabis use during pregnancy. For instance, in Alabama, women have gone to jail for smoking weed while pregnant. Some hospitals have different rules regarding drug testing for new and expecting mothers, and also reporting results to CPS. If you do plan on using cannabis during pregnancy, it’s in your best interest to review your hospital and healthcare providers’ policies first.

Can you Smoke Weed while Breastfeeding?

Unsurprisingly, there’s also limited data on the safety of cannabis use while new mothers breastfeed. “There’s just no research,” says Gill. While a 2015 study found cannabinoids are found in breastmilk, the effects on the baby still aren’t clear.

What is clear is that the human body’s’ own natural endocannabinoid 2-AG, basically the brain’s own version of THC, is passed from mother to child during breastfeeding. This cannabinoid is actually key to keeping newborns alive. Research dating back to 2004 has shown that these compounds stimulate suckling among newborn mice. This could be because endocannabinoids help stimulate muscles in the tongue. Researcher Ester Fride explained that the presence of these cannabinoids may help prevent a disease known as “non-organic failure to thrive,” which is when a newborn baby cannot eat enough food to sustain itself.

Fride has called these endocannabinoids “extremely vital for proper human development.” In some of Fride’s later work, she explains that endocannabinoids play a major role in fetal brain development. She also discovered that these cannabinoids are altered when a pregnant mother is under stress.

Fride’s findings show us that cannabinoids can have a major impact on developing babies. They also show us that these compounds play a much more complicated role in human development than we have previously expected. In certain medical instances, like failure to thrive, cannabinoids may prove to be a potential therapeutic target for treating the disease in the future. “Some might argue that CBD supplementation during breastfeeding can be beneficial to the baby,” says Gill.

However, a 2012 review found that babies exposed to THC through breast milk might have increased risk of the following:

•     Tremor
•     Poor sucking reflexes
•     Decreased feeding time
•     Slow weight gain
•     Changes in visual responses
•     Delayed motor development

Yet, this review also highlighted the difficulty in efficiently studying cannabis use in breastfeeding mothers, and stated that any results should be treated with caution.

Though the above research has pointed out some potential major cons for using cannabis during pregnancy, other studies have suggested that cannabis use while breastfeeding has no apparent effects. Exactly why this is the case is unknown, but it may be partly because young brains don’t process THC in the same way as adult brains.

Research completed in 2004 by Ester Fride, mentioned earlier, proposed that children may be less sensitive to the psychoactive effects of THC. This is because cannabinoid receptors are not fully expressed in developing organisms. This fact led Fride to suggest that cannabinoids be tested as a potential treatment for certain pediatric diseases, such as cystic fibrosis. Of course, this argument is a slippery slope in regards to newborns; clinical trials are needed to determine whether or not this is accurate.

Does Weed Affect Fertility?

Just like cannabis use during pregnancy, the research on weed and fertility is both lacking and conflicting. Gill points me to a 2017 retrospective review that determined “cannabis use had no effect on getting pregnant.”

Although, this conflicts with other research that shows that heavy cannabis use may affect fertility by interfering with sperm count, and ovulation. However, many of those studies were performed on animals. What’s more, in the case of the ovulation study, animals developed a tolerance to THC at around three months and their menstruation and ovulation went back to normal.

How can weed even affect fertility? It all has to do with our body’s system of cannabis receptors, the endocannabinoid system (ECS). While the ECS is known for its role in homeostasis and regulating bodily functions, Gill explains, it also plays a significant role in fertility.

“So in theory, an out of balance endocannabinoid system might negatively affect your ability to get pregnant,” says Gill. “Based on that premise, cannabinoid supplementation could help alleviate the issue. But the truth is, we really have no idea if cannabis directly affects fertility.”

The role of the endocannabinoid system in reproduction is quite complicated. Endocannabinoids and cannabinoid receptors have been found in seminal fluid in men, as well as in the ovaries, fallopian tubes, and placenta in women. Compounds like anandamide, another one of the body’s natural endocannabinoids, can kick-start ovulation when levels are high. In order for life to form, hormonal and endocannabinoid levels need to be just right at precisely the right time. Any imbalance in the system has the potential to cause unwanted results. Exactly what the end result will be, however, is difficult to tell.

So does weed affect fertility? Kind of, but not irreparably so. Using marijuana can hinder the process by decreasing viable sperm in men, and it may make getting pregnant a little harder for women. In men, a low sperm count may continue for as long as you keep smoking weed. In women, however, tolerance to the plant over time seems to mitigate some of the initial effects on ovulation.

The herb might slow things down. But, taking a tolerance break might help speed things up if you’re trying to conceive. We can’t say for sure, though, until more advanced clinical research is performed on humans.