Marijuana Use in Pregnancy and Lactation: Sure it’s Natural, But is it Safe?

Lori Wood, MSN, CNS, RNC-NIC, IBCLC / August 2018

Human milk is always placed as a priority for both term and preterm infants whenever possible as the multiple health and immunity benefits are undisputed (Wood, 2013). Even in cases of maternal medication use, infection exposure, or health issues, the properties of breast milk are often favored and a risk versus benefit appraisal must be considered (Mourh & Rowe, 2017). Policies and statements have long existed to provide guidance and a stance on maternal drug use during pregnancy and lactation. With the continued legalization of marijuana in 29 current states plus the District of Columbia, increasing use among women of child bearing age, and a general consensus that natural is good, many healthcare providers are left wondering what is best (Metz & Stickwrath, 2015).

As the legalization of marijuana both medical and recreational continues, usage among women of childbearing ages rises. Current percentages of reported use are varied, largely attributed to self-reporting. Marijuana user’s honesty regarding use may be influenced by their comfort and trust with those collecting data, as well as the laws in their state of residence. In a report from the American College of Obstetricians and Gynecologists (ACOG), marijuana is the most commonly used illicit drug. 2-5% of pregnant women self-report using marijuana during their pregnancy, but these numbers increase to 15-28% among young women with socioeconomic issues or those who live in urban settings (ACOG, 2017). Of interest is the growing number of highly educated women with steady employment and an annual income of $75,000 or more. These people are turning toward marijuana as a natural cure and treatment for a number of medical maladies. In a recent survey of 10,000 California commercial marijuana customers, 57% were millennials (birthdates between 1983-1996), 21% Generation X (birthdates between 1965-1982) and 15% Generation Z (birthdates between 1996 to now). Almost 93% of this survey includes people of general child bearing years; 32% are women, and 20% are parents. The common desire of these marijuana consumers is to reduce the use of alcohol and pharmaceuticals and enjoy the healing of marijuana (Merwin, 2017).

As society’s increasing approval of marijuana continues, more pregnant and breastfeeding women are turning to marijuana for relief of symptoms such as nausea, anxiety, and to replace medications known to be harmful to the fetus (Merwin, 2017). Women who use marijuana in pregnancy report a higher usage in the first trimester when nausea is highest with decreasing usage often reported by the third trimester (Mourh & Rowe, 2017). Women suffering from bipolar disease often look for replacement medication when pregnant and/or breastfeeding. A Google search of treating bipolar disease with marijuana results in numerous remedial blogs and suggestions for healing in a natural fashion. Many bipolar medications often have detrimental effects to the fetus (Epstein, et al, 2014). For this reason, marijuana is often considered by this population of patients to be a safer, more natural way to treat a serious condition. Because opinions are so varied and research is not plentiful, supportive information for either side of the marijuana issue is readily available (Wilcox, 2016). Use of marijuana during lactation continues after the symptoms of pregnancy are gone in many moms who used during this time. Continued use of marijuana during breastfeeding to treat symptoms and issues could often be replaced with alternative therapies considered safer and more studied (Mourh & Rowe, 2017). A 2014 survey highlighted the most commonly reported reasons for marijuana use in pregnant or breastfeeding moms as: depression, stress relief, anxiety, pain, and nausea and vomiting (Saint Louis, 2014). Many women have incorporated marijuana into their daily lifestyle well before becoming pregnant and wish to continue its use. ACOG reports that 34-60% of marijuana users consider it safe to use during pregnancy and lactation (ACOG, 2017). Because marijuana use is not directly linked to congenital abnormalities, many healthcare providers and people in general, feel it is a safe alternative to medications and support its use. Withdrawals from marijuana in infants is also not noted, lending to the notion that marijuana is safe to use in pregnancy and while breastfeeding. Absence of major anomalies and withdrawal does not allude to safety, especially in the developing neonatal brain (Saint Louis, 2017)!

Another loosely associated support for the use of marijuana in pregnancy and lactation is tied to the endocannabinoid system. The endocannabinoid system (ECS) is present in the developing fetus from approximately week 16 of gestation and is extremely important in the development of the neuronal brain circuit (Volkow, et al, 2016). This system is responsible for the differentiation of stem cells into neurons and axons, guiding the migration of axons and creating the matrix for neurons to plant and establish synapses. The proper development of this circuitry is essential to the continued ability of the fetus to grow and develop a brain ready for higher development and eventual learning. Cognition, suckling, and motor development are all controlled by this system (Fantasia, 2017; Mourh & Rowe, 2017) Cannabinoid receptors, CB1 and CB2, also develop in the brain and peripheral tissue. These receptors are responsive to both natural endocannabinoids which are produced and available in human breast milk as well as phytocannabinoids present in marijuana (Onaivi, 2011). Exposure prenatally to an excess of cannabinoids present in marijuana is thought to oversaturate these receptors. Tetrahydrocannabinol (THC), the main cannabinoid in marijuana is much stronger than those naturally occurring. As THC is passed from the mother to the fetus, it is stored in the fat cells of both (Fantasia, 2017). THC crosses both the placental and blood-brain barrier exposing the fetus and newborn to potentially high levels (Mourh & Rowe, 2017). This THC can be released over time causing increased exposure of the cannabinoid receptors to these substances resulting in changes to normal neural development (Fantasia, 2017). Exposure to these phyocannabinoids has been demonstrated to influence the expression of genes, causing epigenetic changes to cell proliferation, migration of the neurons, and elongation of the axons during fetal brain development (Fernandez-Ruiz, et al, 2004). Disruption of fetal position and axon differentiation can lead to changes in postsynaptic selectivity. Physical, cognitive, emotional, social, and motor function changes have been reported by some; these issues were demonstrated into adult life (Day, et al, 2011)! Proponents of marijuana use in pregnancy and lactation will cite the necessity of these cannabinoids and their natural occurrence in breast milk and the body as a positive reason for marijuana use. At this time with limited randomized controlled trials and true evidence, exposure to phytocannabinoids, in any amount, cannot be deemed safe (Johnson, 2016).

Stronger concentrations of THC can be passed on through the breast milk of moms who use marijuana. While exact levels of marijuana metabolites in breast milk are hard to determine, researches have completed studies which give a generalization. Because THC is stored in fat cells, the breastmilk of moms with chronic and moderate to heavy use of marijuana is found to contain eight times more THC than mom has in her plasma. THC continues to concentrate and remain in human milk resulting in too much for baby. Infants ingest approximately 0.8% of the maternal dose from one marijuana cigarette during each feeding (Djulus, et al, 2005). Because THC is extremely lipophilic and breast milk contains high amounts of fat, THC concentrates in the milk. The THC from that one cigarette will continue to stream into mother’s milk as the average half-life for excretion is 20-57 hours depending on mother’s metabolism. As baby continues to nurse 8-12 times a day, the infant has the potential exposure of about 10% of mom’s intake of THC. If mom consumes more THC edibles or smokes more than one marijuana cigarette, the amount of exposure increases. Multiple studies show that infants born to mothers who use marijuana occasionally, test positive for THC in their urine days after exposure. Positive infant results can continue longer, from 5-13 days following exposure, in babies whose moms use marijuana heavily/chronically (Huestis, 2007; Paramore & Paramore, 2017). Perinatal cannabinoid exposure via mother’s milk has also been shown to change both dopaminergic and opioid receptors in the brain of animals post birth. Rat models were exposed to levels of THC via mother’s milk and these changes were noted (Fernandez-Ruiz, et al, 2004). One study compared postmortem fetal brains of infants exposed to marijuana against those who had not.

Similar changes to dopamine and opioid receptors were seen (Metz & Stickwrath, 2016). Changes in these receptors can be responsible for motor changes and drug seeking behavior, thus a theoretical concern is established (Fernandez-Ruiz, 2004).

Because the concentration of THC in the average marijuana cigarette has increased from approximately 3.4% per cigarette to 12-13% with new genetically modified and commercially grown marijuana, the marijuana smoked or consumed now is not the same that past generations have been exposed to (ElSohly, et al, 2017; Volkow, et al, 2014)! Early studies of the effects of marijuana on the fetus and in breastfeeding are no longer applicable today! A study by Dreher and Associates in 1994 looked at infants in Jamaica. This study compared infants of moms who used marijuana to those whose mothers did not. Comparison of the results of the Brazelton Neonatal Assessment Scale showed no differences at three days and one month of life (Dreher, et al, 1994). Fried reported similar findings in 1982 as well as Tennes and associates in 1985 (Paramore & Paramore, 2017). Higher concentration levels noted in today’s marijuana, however, are exhibiting different effects. Marijuana is changing the critical circuits of the developing fetal and post-birth neonatal brain (FernandezRuiz, et al, 2004; Saint Louis, 2017).

Most research on the effects of marijuana in breast milk in baby surround the area of infant development. As discussed, considerable exposure to THC in utero can have negative effects on the development of the fetal brain. Elevated concentrations of THC in breast milk consumed by the infant can have the same effects. Since the endocannabinoid system is responsible for the normal development of brain circuitry controlling motor development, suckling, memory, and cognitive function, all of these areas can suffer. Multiple studies have been conducted to follow motor development and the achievement of developmental milestones by using the Baley Scale of Infant Development. Infants exposed to marijuana in the first months following birth were noted to have lower psychomotor scores at one year. Results were difficult to isolate however as 84% of the mothers consenting to the study had used during the pregnancy as well as breastfeeding. Slow weight gain has been noted in several studies (Metz & Stickwrath, 2015).

Route of marijuana intake has no difference on maternal plasma levels or infant exposure, therefore all forms of marijuana use, smoking, vaping, and ingestion via candies, cookies, and other edible sources are potentially harmful to infants. Edibles in particular are difficult to judge for novice users. Adults exposed to approximately 10-30 mg of THC will experience the psychotropic effects of marijuana. Edible sources such as cookies usually contain 100 mg of THC. Eating 1/10th of a cookie isn’t a very realistic expectation for most people, making over consumption and true marijuana poisoning a possible reality. Adult users also underestimate the timing of clinical effects with ingestion as compared to inhalation. The effects of marijuana are usually felt within 10 minutes of smoking, while edibles must be digested, resulting in about 30 minutes time for the effects to be felt. This time difference is often not understood, resulting in consuming much more than was needed. Emergency Departments in Colorado report increasing numbers of visits due to marijuana edible dosing errors. In addition, pediatric visits are reported due to unintentional intake of marijuana edibles. With such a wide availability of types of marijuana for commercial use, mothers may be more enticed to try marijuana colorado

and potentially exposed to high dosing with negative outcomes that can be passed to their baby (Monte. et al, 2015).

ACOG and The American Academy of Pediatrics (AAP) both recommend screening for maternal marijuana use at the onset of obstetrical visits. Verbal questioning is the usual form of screening and is acceptable to most patients, although truth in answers may vary (AAP & ACOG, 2012). A study in Pennsylvania where marijuana is legal, unveiled that only 36% of moms who tested positive for marijuana were truthful in disclosure. Selfreporting is often limited by the mother’s perception of trust, communication style of the provider, feelings of guilt or worry regarding judgement, punishment, stigma, or custody issues following birth (Chang, et al, 2017). A non-judgmental and open style of communication both during prenatal visits and following birth at the pediatrician’s office or with healthcare staff including nurses in the neonatal intensive care and maternal units will foster truth and better outcomes. At this time it is suggested that women who use marijuana should be counseled about the possible effects on both the fetus and the developing newborn and assisted with options to discontinue use (ACOG, 2017). Some mothers may be unwilling to do so and upon education and discussion, a plan to reduce use may be created. Assistance with treatment programs may be an option for some. Above all honesty, integrity, and support should be conveyed. Nurses and staff in prenatal counseling positions should consider their own personal biases and be aware of the legal implications in the state of practice to be able to work effectively with women who need guidance.

For staff practicing in hospitals, perinatal units or the NICU, the subject of marijuana use in breastfeeding mothers should be considered, researched, and a unit policy or guidelines developed. If the state of practice has legalized medical and recreational marijuana laws, hospital providers may not be able to force a mom to discontinue the use of breastmilk for her baby. Education sheets and a standard team of people to speak to and counsel mothers should be created. By establishing a team, all members will be able to provide uniform and consistent information. Educating mothers and families about the use of marijuana during breastfeeding can be approached in the same manner as anti-vaccination requests, or refusal of Vitamin K and Erythromycin at birth. The opportunity to present information and assist with a risk versus benefit discussion can be created. After education and discussion, if the mother and/or family still decide to continue using breast milk while mom uses marijuana, an against medical advice or waiver form can be presented and signed.

While current evidence and science points to marijuana being unsafe to use in pregnancy or breastfeeding, not enough research has been established to make a definitive call. The benefits of human milk in the newborn diet are a concrete given; yet marijuana and its effects are not well studied. Current research has a stronger emphasis on the use of marijuana during pregnancy. Use during the postpartum period and during lactation is often confounded by pregnancy use as well; more research on marijuana use during breastfeeding is needed. As societal norms change, and the stigma surrounding marijuana use in general dissipates, women of child bearing years are likely to turn to marijuana for alleviation of medical symptoms. With the message of marijuana and its safety conflicting depending on the source, healthcare providers, nurses, and staff working with the pregnant and breastfeeding woman must do their best to research, understand, and reduce personal bias. Working together with our patients to educate and collaborate, we can provide the best outcomes that our evidence at this time can support.


This article was previously published in Neonatal Intensive Care, Vol. 31 No.1 – Winter 2018



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About the Author


Lori Wood is a Clinical Nurse Specialist at Desert Regional Medical Center, Palm Springs, CA. Lori is certified as a RNC-NIC in Neonatal Intensive Care Nursing and is an International Board Certified Lactation Consultant. She is also a consultant for Medela, LLC.

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