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Cannabis and Pregnancy: The Famous Jamaica Study

Lydia K. RN
mother playing with her toddler son

The Jamaica Study came out almost 25 years ago, but its results are still support cannabis and pregnancy.

A study conducted by the University of Massachusetts reveals that babies born to heavy-cannabis-consuming mothers have better neonatal outcomes than newborns of non-exposed mothers. You may have heard this study  simply called “The Jamaica Study.”  Pro-cannabis mom blogs often cite the official title, “Prenatal Marijuana Exposure and Neonatal Outcomes in Jamaica.” The Jamaica Study was ethnographic research examining neonatal outcomes of: autonomic stability, quality of alertness, irritability, self-regulation, and interaction with caregivers. To their surprise, researchers found evidence that cannabis and pregnancy are compatible.

cannabis, prenatal, studies, pregnancy, medical cannabis, recreational cannabis, Jamaica, Rastafarians, impact, spirituality

Cannabis and Pregnancy Gets Support From Observational Jamaica Study

Ethnographic research is a qualitative method where observers watch participants in the study in their own real life environment.  The participants were mothers from a rural Jamaican setting, a region which has a high population of heavy cannabis consumers. It included twenty-four Jamaican neonates exposed prenatally to cannabis. Twenty non-exposed neonates were the control. A neonate is an infant less than a month old.

Researchers observed the neonates at three days after birth and then again at one month.  The Brazelton Neonatal Assessment Scale was used to evaluate the criteria in all of the babies.

Over Time, Cannabis-Exposed Babies Pull Ahead of Their Peers

There was no significant difference between the two groups of infants at the three day mark.  The results after one month, however, revealed that the cannabis-exposed neonates “[had] better physiological stability and required less examiner facilitation to reach organized states.” These babies also achieved better scores in alertness, irritability and autonomic stability than non-exposed neonates. The exposed neonates had more rewarding interactions with their caregivers.

Assessing Neonates With NBAS

The The Neonatal Behavioral Assessment Scale (NBAS) is a popular neurobehavioral tool Dr. T. Berry Brazelton and his colleagues developed. It describes the newborn’s response to the extra uterine environment and examines the emerging parent to child relationship. The scale comprises 28 behavioral items, each scored on a 9-point scale. It also includes an assessment of the infant’s neurological status on 20 items, each scored on a 4-point scale.

What Does The Jamaica Study Tell Us About Cannabis and Pregnancy?

This study allows us to extrapolate certain key conclusions: “The absence of any differences between the exposed and non-exposed groups in the early neonatal period suggests that the better scores of exposed neonates at 1 month are traceable to the cultural positioning and social and economic characteristics of mothers using marijuana that select for the use of marijuana but also promote neonatal development.”

The implications are that there is no deficit in neurological or behavioral patterns found in babies born to cannabis consuming mothers. Contrary to a widely held belief that cannabis use during pregnancy poses serious threats to the growing child, this study demonstrated the opposite.

In fact, cannabis-exposed neonates showed better outcomes, both behaviorally and neurologically, at one month.

 mother smiling and looking at her newborn

Another Study Followed Cannabis Exposed Babies to Age Five

A separate study, also carried out in rural Jamaica, followed 59 children from birth to age 5 years. Study subjects comprised two groups: 50% exposed to cannabis while in the womb and 50% no cannabis exposure. Surveyors matched populations for age, parity, and socioeconomic status.

The Brazelton Neonatal Behavioral Assessment Scales for infancy and the McCarthy Scales of Children’s Abilities for childhood evaluated the participants. The results showed no significant difference in developmental outcomes between the two groups, except that at 30 days the exposed neonates had more favorable scores on autonomic stability and reflexes. The developmental scores calculated at 4 to 5 years were related to the home environment as opposed to prenatal cannabis exposure. The Jamaica Study supports these findings.

Jamaica has a rich history with cannabis, even though the herb has been illegal in the country for many years. Decriminalization of ganja (up to two ounces) arrived in 2015. The Rastafarians consider ganja as a sacrament and smoke it for inspirational and spiritual connection. Pregnant women continue to smoke ganja as a form of their spiritual existence.

Doctors Still Give Caution to Cannabis and Pregnancy

The AmericanCollege of Obstetric and Gynaecology  still recommends that pregnant women abstain from cannabis with the following advice:

“When marijuana is smoked or eaten, the chemicals reach the fetus by crossing the placenta. Research is limited on the harms of marijuana use during pregnancy. But there are possible risks of [cannabis] use, including babies that are smaller at birth and stillbirth. Using [cannabis] also can be harmful to a pregnant woman’s health. The American College of Obstetricians and Gynecologists recommends that pregnant women not use [cannabis].”

close up of pregnancy belly


Research on cannabis and pregnancy is limited. Can we trust the results of a small sample, observational study? The good news is that researchers, who set this up as a randomized study, paid extreme attention to their sampling techniques. This made sure that despite the small sample size, it was representative of the general population. The final verdict, however, is still out on how cannabis may benefit or harm the developing fetus.

Lydia Kariuki

RN, Expert medical writer who is passionate about cannabis!

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