Science Behind Marijuana and Pregnancy: Is It Harmful?

The relationship between marijuana and pregnancy actually has a very long history.

The oldest preserved evidence is dated back to 2000 BC Mesopotamia and is describing recipes for relieving birth pain in women. Cannabis was a well-known medication used by women, for centuries but what is going on with this topic today?

By now, we all know smoking cigarettes is bad for both the baby and the mother-to-be. Clinicians agree, research has proved, it’s well established — tobacco and smoking are bad and harmful during pregnancy.

On the other hand, what about using marijuana during pregnancy? Marijuana and pregnancy still cause a serious social stigma and it’s something that’s rather avoided than talked about.

Nevertheless, are all those concerns justified?

Once more, as it always comes with marijuana and health, more research is needed to make a final judgment.

In this case, there has always been ethical concerns and dilemma on carrying out experiments on pregnant women, so most of the studies were just observations.

Likewise, there is hardly any research that used edibles or marijuana tea. Everything we have so far has included smoking as a factor.

To be honest, as a result of legalizing the drug on an international level, it’s just a matter of time when the issue of weed’s impact on fetus becomes the number one public concern.

Some studies concluded that consuming marijuana during pregnancy brings some risk to the baby, mother and the whole process of giving birth. Others deny these results, appealing to the lack of introducing other factors which could have had an influence on the overall results.

Also, most of the experiments included both smoking tobacco and marijuana as factors, not separating them for more relevant results, nor there is any research on the influence of different cannabinoids (THC and CBD) during pregnancy.

We have come to the point that in 14 US states, using marijuana during pregnancy is considered child abuse, with possibly serious consequences like having your child taken away by the social services.

Social pressure and the lack of medical research made this possible solution for morning sickness unavailable for millions of women.

Still, marijuana remains the most used prohibited drug used among pregnant women around the world.

So, what does science say about marijuana and pregnancy?

Science behind marijuana and pregnancy

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

That means even if you’re smoking, vaping or eating edibles while pregnant. But, does it have a bad or good effect…or no effect at all?

The research on the prenatal use of marijuana began back in the 1980s when most studies were trying to link preterm birth and low birth weight with cannabis use.

As it happens, almost none of them were focused on long-term possible implications, for example on cognitive deficits. However, results and scientific opinion are diverse.

Most research regarding marijuana and pregnancy has been conducted on animals, like the one giving the substance to rhesus monkey during pregnancy. (1)

The conclusion was simple:

Marijuana consumption during early pregnancy increases the risk of miscarriage.

These were not humans so critics of this study like to point out that the reproductive system in primates is not that similar to humans and neither are their response to drugs.

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 which did not use the substance during the pregnancy and the other group of 44 women which smoked weed on a regular basis.

Dr. Dreher’s team made a series of function tests on babies during different periods after birth (one day to five years of age).

Her findings were really surprising, especially for that time, since babies from mothers who used marijuana had a better score in basic function and reflex tests and were more calm, too.

Dr. Dreher continued to observe the outcome and at the age of five, children took IQ tests while 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 and did not use marijuana 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. Still, we can not tell if the difference in just a few days can make a significant difference.

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

Dr. Conner and her team made a comparison of 31 previously published studies on marijuana use during pregnancy and health after-effects.

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 the influence of both substances.

The other thing they concluded was that mixing tobacco and marijuana increases the risk of preterm birth and lower birth weight.

However, when removing tobacco as a factor, there were no negative effects. So, as they concluded, mixing tobacco and marijuana is probably harmful to the fetus, but still, more longitudinal studies are needed before making any judgment about the long-term consequences.

So, what do all the studies tell us about the prenatal use of marijuana?

Just to go with our own judgment and to wait for more research to better comprehend the issue.

Even the doctor and scientists can’t agree on this. However, one long-term observational study of Jamaican women who used cannabis regularly during their pregnancies and those who didn’t show there was no difference between their children. Still, more scientific research is needed to back up it the findings.

Can marijuana help with morning sickness?

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

Morning sickness

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 mother and the baby.

Interestingly enough, more and more women are turning to use marijuana for help. (4)

In 2014, 4% of pregnant women age between 18 and 44 reported using marijuana for relieving the symptoms, especially during the first trimester of pregnancy — compared to 2.4% in 2002, a statistic which is making medical experts slightly concerned.

Of course, doctors would always recommend approved drugs for morning sickness, such as Zofran, rather than marijuana. Even though there has been a major public scare recently, regarding those drugs potentially causing birth defects.

Medical marijuana 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 medical marijuana act as antiemetics.

If that is something that is proven to be effective, why can’t we use it during pregnancy?

The experience of Dr. Wei-Ni Lin Curry has been discussed among pregnant women suffering from morning sickness.

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

She reported having severe morning sickness and even vomiting blood. She wanted to determine her pregnancy twice before she turned to medical marijuana, smoking just a small amount of it at night which made the sickness stop and her appetite come back.

Believe it or not, Dr. Curry claims 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. And, also, there’s that whole thing of the pharmaceutical industry having their piece of the pie.

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

But, the research did not focus on the outcome of using marijuana. In other words, we don’t know if it made any difference.

Some organizations tried making their point in slightly different kind of way. The Vancouver Island Compassion Society (The VICS) and the BC Compassion Club collected data from an anonymous survey.

In fact, from 84 pregnant women who took part in the questionnaire, 36 of them reported using marijuana occasionally and 33 of them reported the experience was very helpful in fighting the symptoms of morning sickness.

Cannabis has been used as an effective antiemetics drug. While a growing number of women use it to treat their morning sickness, it’s not a qualifying condition to become a medical marijuana patient.

So, can you use marijuana during pregnancy?

Sadly, at this point, I can’t give you the final answer. This whole confusion with marijuana and pregnancy can be a very frustrating thing for future mothers.

There are some medical experts and activist encouraging mothers-to-be to use marijuana during their pregnancy. Still, most doctors would not recommend it.

Take into account the research we’ve discussed earlier and go with your gut feeling. Unfortunately, the decision about using marijuana while being pregnant remains every woman’s personal judgment.

We will know more about marijuana’s influence on a child’s development when more clinical research is conducted.

With marijuana widely becoming legal, I hope it’s just the matter of time before governments start to fund marijuana-related studies.

Can you use marijuana after pregnancy and while breastfeeding?

Once again, the issue of using marijuana during breastfeeding is still controversial among academics and medics. Their results and opinion are divided.

During the breastfeeding period, everything you take will make it’s way to the baby through milk. 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.

During one research published by Katherine Tennes, there was no link found between breastfeeding mothers and use marijuana and negative income on the babies. She observed more than 700 women before and one year after giving birth and concluded there was no difference in the development of marijuana-exposed babies. (7)

However, we all know that infants are more sensitive to toxins and other chemicals than adults.

So, until we know more about marijuana’s influence on babies, 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.
Categories Health

In charge of Greencamp’s health section, with a decade-long experience of using cannabis for stress relief. Her spare time is mostly divided between dancing, traveling and reading.

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