Marijuana and Pregnancy: Is It Safe to Smoke Pot While Pregnant?

Marijuana and pregnancy marijuana while pregnant is usually frowned upon, but is there substantial scientific evidence that clearly shows if cannabinoids harm the child?

We all know that cigarettes are bad for both the baby and the mother, but I wanted to find out if that is the case with cannabis. Marijuana and pregnancy still cause a serious social stigma and it’s something that’s rather avoided than talked about.

The issue we have with this topic is that there have always been ethical concerns about carrying out medical experiments on pregnant women, so most of the studies were just observational.

Also, even those observational studies didn’t use oral consumption as one of the preferred methods—every piece of scientific evidence we have so far used smoking as a cannabis consumption method.

Some studies (which we’ll get to later in the article) concluded that using marijuana during pregnancy poses a risk to both the baby and the mother and some claim that using cannabis while pregnant is completely safe.

Also, most of the experiments (except one) included smoking both tobacco and marijuana. Separating these two compounds would produce more relevant results.

We also haven’t seen any research on the influence of different cannabinoids (THC and CBD) on the entire pregnancy.

Nevertheless, many pregnant women still decide to use cannabis while pregnant. Let’s find out why.

Research on using marijuana during pregnancy

When you are expecting, everything you eat, drink and even put on your skin may affect the baby.

Early research on cannabis and pregnancy was usually trying to link preterm birth and low birth weight with cannabis use.

As it happens, almost none of the early studies were focused on long-term possible implications, for example on cognitive deficits in children whose mothers used cannabis.

Most research regarding marijuana and pregnancy has been conducted on animals, like the study titled “Effects of delta 9-THC, the principal psychoactive component of marijuana, during pregnancy in the rhesus monkey.” (1)

Their conclusion was simple:

Marijuana consumption during early pregnancy increases the risk of miscarriage (in rhesus monkeys). 

Many critics of this study argue that the reproductive system in primates is not that similar to humans and neither is their response to THC.

One of the most thorough long-term studies on marijuana and pregnancy was conducted in ‘80 by Dr. Melanie Dreher.

Since smoking marijuana in Jamaica is so widespread, she compared two groups of women: One group did not use cannabis during pregnancy and the other group of 44 women smoked pot on a regular basis throughout their pregnancy.

Dr. Dreher’s team made a series of function tests on babies during different periods after birth (up until the kids were five years old).

Their findings were really surprising, especially for that time, since babies from mothers who used marijuana scored better in basic function and reflex tests.

Dr. Dreher continued to observe the kids and at the age of five, children took IQ tests. At this point, some other factors were taken into account, like school and home environment.

Her conclusion was clear:

There was no difference between children whose mothers used cannabis and whose mothers did not use cannabis during pregnancy.

This was the biggest human study ever, so it’s no surprise that Dr. Dreher wanted to continue with follow-up studies and repeat the tests after some time.

After the results of her findings were made public, she lost her funding and was suggested to continue the research with the scholar who had opposite thoughts and conclusions on the issue.

Unfortunately, that was when her research ended. Conspiracy ahoy.

A study published in 2012 suggested there was a negative outcome on pregnancy and marijuana consumption, primarily causing earlier birth, with lower birth weight. (2)

As it turned out, on average, mothers who used the substance gave birth at 38.1 weeks, while mothers who didn’t consume it delivered at 38.7 weeks.

One of the latest systematic review papers regarding the prenatal use of marijuana was conducted and led by Dr. Shayna Conner from the University of Washington. (3)

What Conner’s team concluded was that almost all research done by now considered the use of both marijuana and tobacco during pregnancy. There are barely a couple of scientific papers that separate these two substances.

Dr. Conner’s team also concluded that mixing tobacco and marijuana increases the risk of preterm birth and lower birth weight.

So, as they concluded, mixing tobacco and marijuana is probably harmful to the baby, but still, more longitudinal studies are needed before making any judgments about the long-term consequences.

One long-term observational study showed that there are no dangerous health effects of using cannabis during pregnancy, however, several more papers showed that mixing tobacco with marijuana may increase the risk of preterm birth.

Can marijuana help with morning sickness?

Almost everyone knows that morning sickness is one of the most common symptoms of pregnancy.

Around 70-90% of women suffer from nausea and vomiting, usually between the 4th and 16th week of pregnancy. And almost 10% suffer from it after the 20th week.

Hyperemesis gravidarum (HG), the severe form of morning sickness can lead to weight loss, dehydration, fainting and even a life-threatening state for both the mother and the baby.

Interestingly enough, more and more women are turning to marijuana for help.

In 2014, 4% of pregnant women reported using marijuana for relieving pregnancy symptoms, especially during the first trimester—this is an increase compared to 2.4% in 2002, a statistic making medical experts slightly concerned. (4)

Of course, doctors are always going to recommend FDA approved drugs for nausea, such as Zofran, rather than marijuana.

Medical cannabis is an already known and proven drug for treating nausea and vomiting, especially in cancer patients going through radiation or chemotherapy. Research has shown that cannabinoids in the medical marijuana act as antiemetics.

The experience of Dr. Wei-Ni Lin Curry is often referenced among pregnant women suffering from morning sickness.

At the time, she was a Ph.D. student at UCLA and she was brave enough to publish a scientific paper based on her own experiences with marijuana in treating hyperemesis gravidarum. (5)

She reported having severe morning sickness and even vomiting blood before she turned to medical marijuana. To find relief, she was consuming just a small amount of pot at night which made the sickness stop.

Her appetite soon came back.

Believe it or not, Dr. Curry claims that marijuana saved her child’s life.

There are a number of stories like this—women suffering from morning sickness or HG, turning to marijuana while doctors turn their backs on their positive experience.

The way I see it, the major problem is not having enough quality research done on the effects of marijuana on morning sickness.

In 2014, a group of researchers published an article which said that Hawaiian women who suffered from severe morning sickness were more likely to use marijuana during their pregnancy. (6)

Some organizations tried to make their point in a slightly different way:

The Vancouver Island Compassion Society (The VICS) and the BC Compassion Club collected data from an anonymous survey.

From 84 pregnant women who took part in the questionnaire, 36 reported using marijuana occasionally. From them, 33 reported that cannabis was very helpful in fighting the symptoms of morning sickness.

Should you use marijuana during pregnancy?

Sadly, at this point, I can’t give you a definitive answer.

There are medical experts and activists who encourage mothers-to-be to use marijuana during pregnancy. Still, most doctors would not recommend it.

Take into account the research we’ve discussed earlier and also consider the fact that smoke (by itself) is toxic and harmful to the baby. So I would personally avoid smoking altogether.

There are other alternatives for consuming cannabinoids and they include making pot brownies, cannabis butter (for infusing in other meals) and weed tea.

Can you use marijuana after pregnancy and while breastfeeding?

Once again, the issue of using marijuana while breastfeeding is controversial.

During the breastfeeding period, everything you take will make it’s way to the baby. Since there is almost no research on marijuana effects on newborn babies, most experts advise nursing women not to use marijuana during the breastfeeding period.

I have found a study dealing with this particular issue and it argues that using cannabis while breastfeeding is perfectly safe. The study observed more than 700 women before and one year after giving birth and concluded there was no difference in the development of cannabinoid-exposed babies. (7)

Until we know more about marijuana’s influence on child development, it’s safer not to use it during those few months of breastfeeding.


  1. Asch RH, Smith CG; Effects of delta 9-THC, the principal psychoactive component of marijuana, during pregnancy in the rhesus monkey; The Journal of Reproductive Medicine; December 1986; 31(12):1071-81.
  2. Hayatbakhsh MR, Flenady VJ, Gibbons KS, Kingsbury AM, Hurrion E, Mamun AA, Najman JM; Birth outcomes associated with cannabis use before and during pregnancy; 2012; Pediatric Research; 71:215–219.
  3. Conner SN, Bedell V, Lipsey K, Macones GA, Cahill AG, Tuuli MG; Maternal Marijuana Use and Adverse Neonatal Outcomes: A Systematic Review and Meta-analysis; Obstetrics and Gynecology; October 2016; 128(4):713-23.
  4. Brown QL, Sarvet AL, Shmulewitz D, Martins SS, Wall MM, Hasin DS; Trends in Marijuana Use Among Pregnant and Nonpregnant Reproductive-Aged Women, 2002-2014; JAMA; 2017; 317(2):207-209.
  5. Curry WNL; Hyperemesis Gravidarum and Clinical Cannabis: To Eat or Not to Eat?; Journal of Cannabis Therapeutics; 2002; 2(3/4):63-83.
  6. Roberson EK, Patrick WK, Hurwitz EL; Marijuana Use and Maternal Experiences of Severe Nausea During Pregnancy in Hawai‘i; Hawai’i Journal of Medicine and Public Health; September 2014; 73(9): 283–287.
  7. Tennes K, Avitable N, Blackard C, Boyles C, Hassoun B, Holmes L, Kreye M; Marijuana: prenatal and postnatal exposure in the human; NIDA Research Monograph; 1985;59:48-60.
About the author
Helena Miles

Experienced journalist with a decade-long experience of researching cannabis. She has been featured in many prominent outlets, such as The Growth Op, National Post and The Province.

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