The Serious Effects of Marijuana on Unborn Babies Every Pregnant Woman Should Know

Pregnant woman holds her pregnant belly.

During pregnancy, most women try to provide ideal environments for their babies. They stop smoking, stop drinking and stop using drugs. But some women have a different idea about the use of marijuana during pregnancy. In fact, there are some doctors who even recommend using marijuana to help with nausea during the early months. In the world of social media, marijuana use during pregnancy is not only frequently recommended as a remedy for nausea, it’s absolutely popular.

Is the use of marijuana to cope with nausea a smart move? Is the use of ANY drug during pregnancy advisable? Three researchers from the American Academy of Pediatrics undertook a review of dozens of studies and bodies of research so they could compile a broad look at this situation. Here’s a selection of their findings.

How Many Pregnant Women are Consuming Marijuana?

The answer to that question depends on which segment of society you’re looking at.

  • 4.9% of pregnant women ages 15 through 44 reported recent use of marijuana
  • For comparison, 11% of non-pregnant women reported use
  • Among 18-25 year old women, 8.5% reported recent use
  • Among 26-44 year old women, 3.3% reported use
  • Among 15-17 year old women, 14.6% reported recent use of illicit drugs and marijuana is the most widely-used drug among pregnant women
  • In Vermont, 9.4% of pregnant women reported marijuana use (2013)

However, studies of urban, young and socioeconomically disadvantaged pregnant women showed marijuana use between 15% and 28%, depending on the study.

Among those using marijuana during pregnancy, use dropped to half in the second trimester and then half again in the third.

What are the Possible Effects of Using Marijuana During Pregnancy?

Before a woman decides to use marijuana during pregnancy, it would be a very good idea to know the effects of this drug on her unborn baby. Here are some of the results of this research.

Newborn baby.
  • The primary psychoactive ingredient of marijuana, THC, readily passes through the placenta to be received by the fetus
  • THC is highly attracted to fatty tissues and the baby’s developing brain is very fatty, meaning that the baby’s brain will attract concentrations of this drug
  • The fetus’s blood concentration of THC will be between one-third to one-tenth of the mother’s
  • Infants prenatally exposed to THC had a decrease in birth weight and lower Apgar scores*
  • Women who smoked not only marijuana but also tobacco were at increased risk of preterm delivery, reduced birth weights and decreased head circumferences
  • Marijuana-using women were more likely to experience stillbirths

Some studies reviewed by these researchers examined differences in the baby’s behavior in the first days or month of life. Here’s some of abnormal responses noted by these studies:

  • Increased tremors and prolonged and exaggerated startle reflexes
  • Abnormal sleep patterns
  • Poor responses to visual stimuli
  • Abnormal high-pitched cries

Later in life, testing showed more differences between children exposed to marijuana in utero and those who weren’t.

A young child tries to put on his shoes.
  • At four years of age, these children scored lower in verbal reasoning and memory tasks
  • At six, they tested lower in language comprehension, memory and reading tasks that require sustained attention
  • Children with higher doses of prenatal exposure demonstrated higher levels of impulsive and hyperactive behavior
  • At 9 through 12 years of age, exposure was associated with lower executive function tasks such as impulse control and visual problem-solving
  • At 13 through 16 years of age, problems were noted related to attention, problem-solving and analytical skills requiring sustained attention
  • At 10 years of age, children whose mothers smoked at least one joint per day during the first trimester showed deficits in reading comprehensive and overall underachievement

Sometimes these results appeared in one study but not in other similar studies. The most important thing is for women who are or might become pregnant to do their own homework before deciding to use marijuana to cope with nausea or to just use the drug because they want to.

Mothers-to-be might also consider the long-term effects of exposure to THC in the womb. A 2009 study revealed the fact that THC can remain stored in fatty tissues for a long period of time. In fact, it’s possible for this drug to be released by the body during heavy stress and food deprivation to such a degree that THC can be detected in the blood. Could young people who were exposed to THC in utero possible experience a later release of this stored THC into their bloodstreams? What would the effect of this release be? Could it affect a child’s mental state and ability to learn?

We don’t have answers to these questions yet. And we don’t know if a child prenatally exposed to THC will be attracted to this drug when he or she gets older. Is it possible that this child might even be more susceptible to addiction to marijuana?

Because we don’t know these answers either, pregnant women have important choices to make about the health and well-being of their babies. It’s vitally important to become better informed before making these choices.

To read the research this article is based on, click here.

*Apgar scores evaluate a newborn’s appearance, pulse, respiration and other factors.


Karen Hadley

For more than a decade, Karen has been researching and writing about drug trafficking, drug abuse, addiction and recovery. She has also studied and written about policy issues related to drug treatment.