Marijuana And Pregnancy #4: Does Marijuana Increase Risk Of Premature Birth?

Potential risks of marijuana use during pregnancy is nerve-racking for expecting mothers. But can the herb really increase the risk of premature birth?

Apr 3, 2016

So far in our cannabis and pregnancy series, we’ve looked at marijuana’s impact on fertility and the debate on using the herb while breastfeeding. We’ve also given you a glimpse into what cannabis does inside the womb. Now, we’re going to address a major point of concern for expecting mothers: does marijuana increase the risk of premature birth? Unsurprisingly, research results are mixed. 

What is premature birth?

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Medically speaking, premature or preterm birth occurs when a baby is born at least three weeks before the official due date. That is, born before the baby reaches the 37th week inside the womb. A normal pregnancy typically lasts about 40 to 42 weeks.

What are the complications of premature birth?

Preterm birth may lead to several short-term and long-term complications for the baby. According to the Mayo Clinic, some of the common developmental risks include:

Short-term complications:

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  • Respiratory issues: A premature baby may have a premature respiratory system. Depending on how early the baby is born, it may not have developed the breathing capabilities of a healthy, full-term infant. Some breathing issues may include apnea, certain respiratory diseases, and difficulty expanding or contracting the lungs normally.
  • Brain issues: Preemie babies also face a greater risk of brain hemorrhages. These hemorrhages are typically not very large, but internal bleeding can do significant damage to the infant over time.
  • Heart issues: Due to a lack of complete heart development, a premature baby may be born with heart defects. Most of the time, these defects will close on their own after a while. But, these defects can cause more serious complications if left untreated.

Other short-term issues include the inability to properly maintain bodily temperature, metabolic difficulties, and an increased risk in developing conditions like anemia, jaundice, and a greater likelihood of developing an infection.

Long-term complications:

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While short-term complications typically go away with time and proper medical care, there are several life-long issues associated with premature birth. Preemie babies are are associated with increased risks of the following:

  • Cerebral Palsy
  • Decreased cognitive functioning
  • Behavioral issues like ADHD
  • Increased chance of Sudden Infant Death Syndrome (SIDS)
  • Issues with vision, hearing, and dental development

Does marijuana increase the risk of premature birth?

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Studies on marijuana and premature birth have produced results that are quite mixed. On one hand, there have been findings that suggest using marijuana prior to pregnancy does lead to an increased likelihood of preterm delivery.  But, studies about marijuana use during pregnancy have yet to find a firm statistical link. Here is a brief overview some of the research available on the topic:

Prior to pregnancy

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In 2012, researchers from the University of Adelaide in Australia listed previous marijuana consumption as a contributor to premature birth. The study examined 3000 first-time mothers in Auckland, New Zealand and Adelaide, Australia.  Researchers found that risks of preterm delivery included everything from a family history of low birth-weight to marijuana use to maternal diabetes and a history of vaginal bleeding.

Though  prior  marijuana was just one factor in a long list, researchers  found that frequent marijuana use  doubled the chance of premature  birth.

The hope of the study was to aid in eventually determining when mother’s are at risk of delivering early. However, the wide variety of factors that positively attributed to preterm birth makes determining precise risks a little tricky. As cited by Jezebel, former March of Dimes Medical Director, Dr. Michael Katz explained:

“I would not attribute much importance to that other than, ‘Ok, it’s an observation.’ Certainly, if you were a woman trying to become pregnant and you asked me ‘Should I use marijuana?’ My answer would be ‘no’.”

Of course, most medical professionals would not encourage expecting mothers to use cannabis. From the eyes of the healthcare industry, the less potential risk factors during pregnancy the better.

Jezebel also pointed out that it is unclear whether or not marijuana use leads directly to premature birth, or if other lifestyle and socioeconomic factors are the real contributors. One 2005 literature review found that frequent marijuana use in females was strongly correlated to traumatic experiences or victimization. Though that’s hardly the case for every female cannabis user, stress is also a key risk factor for premature birth.

During pregnancy

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As mentioned in our piece on marijuana’s effect inside the womb, women around the globe have been using cannabis as a medical aid both pre and post-pregnancy for centuries. But, when it comes down to the precise scientific research on the risks of prenatal cannabis use results are pretty mixed.

A 1995 study published in General Obstetrics and Gynecology  tested the birth outcome of women who had used cocaine and/or marijuana during pregnancy. Relying on data gathered from seven different university pregnancy clinics, the team looked at the results from 7470 women from 1984 to 1989. 11% of which used cannabis while pregnant.

The study found no adverse outcomes relating to marijuana use and either pre-term brith or low birthweight. This is interesting, since mother’s who smoked tobacco had a 15% chance of delivering with a low birth-weight.

Another 2012 study published in Pediatric Research suggested that there is, in fact, a correlation between marijuana use during pregnancy and negative birth outcomes. Some of these poor outcomes include a lower gestational age and lower birth weight.

But, here’s the thing: the results are statistically significant, but when it comes to gestational age, the average  difference is about a week. According to the study, women who did not use cannabis during pregnancy typically gave birth at the 38.7-week mark. Those who used marijuana while pregnant gave birth after 38.1 weeks.

What difference does giving birth a few days earlier really make? It’s difficult to tell. An important observation, however, is that both of these figures do not meet the definition of preterm birth. Though, the slightly  lower age for cannabis-exposed babies indicates that more of those infants were born preterm. Those that had used cannabis regularly prior to pregnancy had an average gestational age of 38.6 weeks versus non-users’ 38.7 weeks.

Though these numbers do not appear to be all that much different, the study authors conclude:

If we assume there is a causal relationship between the exposure and outcome, 2.5% of low birth weight, 1.5% of preterm delivery, and 2.7% of admission to the NICU could be prevented if pregnant women did not use cannabis during pregnancy in this tertiary hospital setting.

So, are there risks?

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Pregnancy is an unbelievably complicated natural event. Everything from diet to different environmental factors can influence a birth outcome. It makes sense that marijuana can have an impact on a fetus during pregnancy, but to what end is very difficult to determine.

Another early study published in 1983 examined the medical records of 12,424 different pregnancies and found that there seemed to be more instances of preterm birth, low birth weight, and physical malformations in those born to marijuana-consuming mothers. BUT, the results were not statistically significant.

So, even in a study that large, the statistical results were inconclusive.

What we do know for sure is that many women out there use marijuana to mitigate some of the harsh side effects of pregnancy, and a large number of these women have had successful pregnancies.

Consuming marijuana by no means guarantees that you will go into premature labor. Though, there has been some evidence that it may increase the risk. Right now it is difficult to tell if marijuana alone increases this risk or if it is one part in a larger combination of factors.

As with most research on marijuana and pregnancy, scientific opinion on the subject is divided. Medical professionals urge mothers to proceed with caution, but many mothers argue that they have used cannabis during pregnancy without issue.

Proud cannamamma’s like Jenna Hoch have come out of the closet for pro-marijuana use as an alternative medicine to traditional pharmaceuticals like Zofran and Phenergan. Both of these drugs are often prescribed for intense bouts of nausea and vomiting that often accompany difficult pregnancies. Hoch writes for Ladybud:

Cannabis saved my pregnancy with my son, made my pregnancy with my daughter tolerable, and helps me in my day-to-day life.

The American Academy of Pediatrics (AAP) has also looked into the overall effects of prenatal marijuana use. In 2013, the AAP published a literature review which examines the long and short term effects of prenatal marijuana, alcohol, cocaine, tobacco, opiates, and methamphetamine. With marijuana, the primary focus of concern was on the herb’s impact on fetal neurodevelopment  and long-term alterations in behavior.

Unlike a few commonly cited studies, however, the review did not fight a significant correlation between marijuana use and low birth weight. In fact, the AAP states:

In general, marijuana has not been associated with fetal growth restriction, particularly after controlling for other prenatal drug exposures.

A difficult decision

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Unfortunately, if you are newly expecting and want a clear-cut answer on whether or not consuming marijuana leads to premature delivery, you may find yourself a little confused. As things stand now, there seems to be a risk of a risk. But, there is little out there to tell you how you should  weigh that information.

Overall, choosing to consume marijuana while pregnant is an extremely personal decision. The best thing you can do is read what information is available, and make informed decisions.

With medical and recreational cannabis becoming increasingly available in the United States, state governments are trying their best to dissuade expecting mothers from consuming marijuana while pregnant. In Oregon you can expect to recieve a warning along with your purchase that is very similar to the warning that is listed on bottles of alcohol or cigarette packages.

Yet, again, many of the effects of consuming marijuana while pregnant are highly debated. Scientific research is at odds with anecdotal evidence and a long human history of cannabis use. Talking to both your doctor as well as mothers who have opted to use the herb while pregnant may give you some more insight into the current pregnancy debate.

But, does marijuana increase the risk of premature birth? It’s a little hard to say. This article only touches on the tip of the iceberg when it comes to the plant’s impact during pregnancy. To settle the score once and for all, we’ll need time and a political climate that will allow medical professionals to conduct real clinical research.

What do you think about the evidence presented in this article? Is it worth the risk? Let us know on social media or in the comments below. We’d love to hear from you!

Apr 3, 2016