by Seshata on 24/12/2012 | Consumption Medicinal

Cannabis Use During Pregnancy

Pregnancy The issue of whether it is safe to use cannabis during pregnancy is one that has caused a great deal of controversy in recent years, as this beneficial herb becomes ever more medically and socially acceptable, and consumption rates continue to climb. Current consensus holds that heavy cannabis use during pregnancy may lead to a reduction in infant birth weight, and possibly increase the risk of conditions such as pre-eclampsia. However, the extent to which this occurs may depend on the method of consumption, as well as various other factors.


The issue of whether it is safe to use cannabis during pregnancy is one that has caused a great deal of controversy in recent years, as this beneficial herb becomes ever more medically and socially acceptable, and consumption rates continue to climb. Current consensus holds that heavy cannabis use during pregnancy may lead to a reduction in infant birth weight, and possibly increase the risk of conditions such as pre-eclampsia. However, the extent to which this occurs may depend on the method of consumption, as well as various other factors.

Cannabis Use During Pregnancy

New research suggests a link between cannabis and early developmental problems

It may be safe to administer small quantities of cannabis at certain points throughout a pregnancy, and opting for a method other than smoking may reduce the risk of developmental problems. However, a recent study found that in the very early stages of pregnancy, even slight variation in endocannabinoid levels could affect embryonic development. Researchers found that either silencing or enhancing the endocannabinoids THC and anandamide in pregnant mice altered the rate at which new placental cells (specifically trophoblasts) form and migrate towards the wall of the uterus.

Although the results have not been replicated in humans, the similarity between the function of the endocannabinoid system in mice and humans led the researchers to conclude that “exposure to cannabis products may adversely affect early embryo development that is then perpetuated later in pregnancy”.

Under normal circumstances, the trophoblasts combine with the endometrium to form the placenta, so that the embryo can receive the nutrients it needs to survive. Reduction in the trophoblast migration rate can cause irregularities in fetal implantation, which may increase risk of miscarriage and later developmental issues. Early trophoblast dysfunction has also been implicated in later miscarriages (up to 20 weeks), involving reduction in placental activity and fetal growth before fetal death ultimately occurred. However, further research is required before firm conclusions can be drawn on the relationship between endocannabinoid levels and trophoblast dysfunction.

Cannabis use in early pregnancy and brain dysfunction in later life

The researchers also postulated that as the endocannabinoid system is so closely linked with neuronal activity in the central nervous system, use of cannabis in early pregnancy may have an effect on initial brain development. Similarly, other studies have determined a link between maternal cannabis use and likelihood of psychosis emerging in teenage offspring. THC, which can pass through the placental barrier to directly affect the developing fetus, is particularly considered to influence the development of cognitive skills.

However, a study by the Christchurch School of Medicine (New Zealand) found that while maternal cannabis use was associated with detectably lower birth weight, this reduction averaged just 90g lighter (considered statistically insignificant), and there was no link to miscarriage or postnatal special care admission for the infant. Another study in Boston found that white women who used cannabis experienced reduction in infant birth rate and increased risk of premature delivery, but non-white women were at no greater risk beyond that already associated with ethnicity.

The effect of culture, ethnicity and socio-economic background

An oft-cited study, Effects of Marijuana Use during Pregnancy on Newborn Cry (Dreher et al, 1989), demonstrated that infants of cannabis-smoking mothers in Jamaica exhibited cries that were shorter in duration, more dysphonic (hoarse), and lower in pitch. These acoustic characteristics are thought to present commonly in infants who experienced perinatal risk, and who often go on to exhibit developmental disorders. Interestingly, this effect was limited to cannabis-smoking mothers; those that ingested cannabis tea delivered offspring with cries within the normal acoustic range.

Cannabis Use During Pregnancy

Dreher went on to document the development of 56 Jamaican children, through gestation to 5 years old, half of whose mothers had consumed cannabis with varying frequency during pregnancy. No discernible difference was noted in birth weight between groups. When the infants were tested according to the Brazelton Neonatal Behavioral Assessment Scale (NBAS), there was initially no difference, but by 30 days the offspring of those who used cannabis (both smoked and ingested as tea) were scoring significantly higher on the reflex and autonomic stability (ability to regulate the autonomic nervous system) assessments. Children of using mothers were less irritable and socialized more easily; the mothers themselves reported experiencing relief from stress and nausea during pregnancy.

Social acceptance of cannabis may reduce risk of developmental problems

However, in this sample, cannabis-using mothers were often of greater economic independence, and more frequently enjoyed the benefits of close, extensive social networks. This cultural phenomenon is well-established in Jamaica, where social smoking is seen as a way to strengthen relationships; furthermore, communal-style living arrangements are relatively common among the various spiritualist groups found in the country. Indeed, the heavier the use of cannabis, the greater the woman’s level of independence and social integration. This rich environment may in part explain the improved development in the offspring of users.

Conversely, in countries where cannabis remains illegal and socially unacceptable, users are associated with lower educational attainments, lower income, greater dependence on welfare, and a lower level of overall life satisfaction. Polydrug dependence is also far more likely in countries where cannabis remains illegal than in those countries that tolerate and accept its use. Furthermore, the heaviest users in the Jamaican study consumed cannabis every day, whereas the Boston study documented “occasional” and “at least 2 or 3 times monthly” usage, with no everyday users. To ascertain the exact relationship between problems in pregnancy, ethnicity, and cultural attitudes to cannabis, further cross-national research must be done, with care taken to assess the effect of frequency of usage.

Cannabis compared to other herbal remedies for morning sickness

While it may be wise to avoid consumption of cannabis if attempting to become pregnant, as (similarly to alcohol) even small quantities in the first few days may disrupt initial fetal growth, many women are opting for cannabis tea as a relatively safe and side-effect-free antiemetic to combat prolonged nausea. No pharmaceuticals are approved for morning sickness in the USA, partly due to the panic caused by Thalidomide in the 1960s, and relatively few are available elsewhere. According to many enthusiasts, herbal cannabis drunk as a infusion is simply another remedy in a naturopathic pharmacopeia which has been used for centuries around the globe.

Cannabis Use During Pregnancy

Studies have been done on the safety and efficacy of common herbal antiemetics used in pregnancy. While research on ginger confirms  it has an antiemetic effect greater than a placebo, there is also a suggestion that it leads to a sharp increase in early miscarriage in rats. Peppermint, another widely used anti-nausea remedy, may also stimulate bleeding and increase miscarriages; ginseng can cause over-production of hormones and even pre-sexual maturation in newborns. While it is thought these incidences arise so infrequently as to be of negligible significance, caution is advised when seeking to self-medicate with these herbal remedies.

Countless women have used these remedies over thousands of years, with little discernible detriment to overall societal health. As with all medications, seeking advice from a trusted healthcare practitioner is critical before embarking on a course of treatment. However, it is likely that cannabis is in fact safer than several herbal remedies, and also than many anti-nausea medications currently in use throughout the world.

As more research is done on the precise interactions between individual cannabinoids and how they affect fetal development, what constitutes “safe” and “unsafe” consumption will become clear. This classification will depend on numerous factors, including the type of cannabis consumed and the ratio of cannabinoids it contains, the method of consumption, and even the socio-economic and ethnic background of the mother.

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