Women’s Health: Cannabis Use During Breastfeeding
The Latest Research
With increased legalization of cannabis, the stigma surrounding use is waning, and women of all ages are increasingly turning to cannabis for a variety of reasons, such as alleviating anxiety and stress, for help with gastrointestinal issues, and at the end of the day to wind down instead of their traditional glass of wine. One potential issue, however, is the safety of cannabis use in women in childbearing years, particularly while breastfeeding.
Helping a new mother make this important decision that might affect the health of her newborn is complicated by several factors. One issue is that most of the available studies are not focused solely on cannabis use during lactation; they tend to focus on the full gestational cycle from preconception through nursing and beyond. Studies focused on breastfeeding alone are biased due to small sample size, possible confounding of a high correlation of cannabis use with alcohol and tobacco use,1 and limited postpartum follow up.2 Health care professionals who treat breastfeeding patients must make their best judgments despite the paucity of available research specifically focused on women who do not use cannabis while pregnant and begin use while breastfeeding.
In Canada, where it’s legal throughout the country, cannabis the most used substance. The National Cannabis Survey, conducted in 2019, reported that 15% of Canadians had used cannabis in the past 12 months.1 Studies based in Canada are good indications of cannabis use trends due to the country’s total legal status.
Professional guidelines clearly advise against any cannabis use during breastfeeding. The American College of Obstetrics and Gynecology (ACOG), the gold standard for US-based clinicians providing obstetrical service to patients in this country, published clinical practice guidelines recommending that breastfeeding mothers completely avoid cannabis use due to insufficient data to evaluate the effects of cannabis on the newborn. Also included in the ACOG guidelines are concerns regarding cannabis use disorder and the need for further high-quality studies to inform clinicians about how to make sound recommendations for their patients.3 The American Academy of Pediatrics also advises against cannabis use by breastfeeding women,4 as do most health care providers who treat lactating women.
The opinions of an increasing number of health care providers, however, are not as black and white on the subject. With conflicting data available, documented use of cannabis for more than 4,000 years, the growing number of lactating women using it, and even some studies concluding little to no differences when comparing infants of cannabis-using mothers with those who abstain,5 providers are making patient recommendation on a case-by-case basis. Even a recent statement published by the CDC provides conflicting information. Under a section titled, “Is it safe for mothers who use marijuana to breastfeed?” it clearly states in bold, “Data are insufficient to say yes or no,” yet the webpage leads with this: “Using marijuana while breastfeeding can allow harmful chemicals to pass from the mother to the infant through breast milk or secondhand smoke exposure. To limit potential risk to the infant, breastfeeding mothers should be advised not to use marijuana or products containing cannabidiol (CBD) in any form while breastfeeding.”6
Cannabinoids in Breastmilk
In 2017, a survey of clients of the US WIC (Women, Infants, and Children) program revealed that about 18% of women used cannabis at least once while breastfeeding7—these among respondents who self-identified their cannabis use. The prevalence is probably higher since many patients do not report their use while breastfeeding due to stigma, policies by institutions and states regarding drug testing, and the legal ramifications for pregnant or lactating women who consume cannabis. Each state and institution has its own set of guidelines regarding reporting breastfeeding cannabis mothers who use cannabis to Child Protective Services, a practice that is somewhat antiquated.
The real issues at hand are whether THC and CBD can be detected in the mother’s breastmilk and, if so, what the ramifications are in the newborn. The pharmacokinetics of cannabis in breastmilk is poorly understood, again based on the lack of high-quality studies. Both THC and CBD have been detected in breastmilk.8 THC is present approximately one hour after ingestion. Concentrations are highly variable and dependent on maternal dose and frequency of use.4 Due to their high lipophilicity, both THC and CBD concentrations may also vary depending on the percentage of maternal body fat.9 While THC is detected in breastmilk in small quantities, studies indicate detection duration ranges from six days to six weeks.10 Measurement of cannabis metabolites in breastmilk is varied, in part due to macronutrients in foremilk and hindmilk. Some studies indicate that, on average, the baby gets 2.5% of the maternal dose through breastmilk. Another determining factor is the frequency of maternal use. The highest concentration of THC in breastmilk occurs one hour after consumption, with concentrations declining over the next eight hours.2 Metabolites of cannabis, specifically THC, 11-OH-THC, THC-COOH, diOH-THC, THC-COOHglucuronide, CBD, 7-OH-CBD, 7-CBD-COOH, and CBN10 have been found in infant feces and urine with milk-to-plasma ratio as high as 8:1 in chronic heavy users. These data suggest cannabis might be absorbed and metabolized by the infant.11 Research on CBD in human breastmilk is nonexistent, making it even more difficult to provide advice to new mothers. CBD products might be contaminated with pesticides, bacteria, and fungi, so it is best for nursing mothers to abstain from using CBD altogether unless it is from a reputable source.6
Effects on Baby
Low-evidence level studies have shown an association between cannabis use during lactation and decreased infant motor development.10 Others have shown an association of slightly shorter stature, sedation, growth delay, low tone, and poor sucking.4 One implication for breastfeeding mothers is they cannot pump and dump, as is customary after alcohol intake, to avoid transmission of cannabinoids to their babies. Another potential issue is that some mothers choose to stop breastfeeding prematurely due to the unknown effects of cannabis on babies, even though breastfeeding is recommended as the best source of nutrition for as long as possible. A study in Canada reported that only 58% of women who used cannabis continued breastfeeding past nine weeks postpartum compared with 79% of women who did not use cannabis.1 The many benefits of breastfeeding last during a child’s life. Health benefits of breastfeeding in the first six months of infant life include decreased infant risk for a variety of health conditions, including diarrhea, type 1 and 2 diabetes, childhood cancer, obesity, respiratory infections, and even infant mortality. For all the above reasons, the World Health Organization recommends exclusive breastfeeding for the first six months of an infant’s life.12 In addition, studies indicate that children of mothers who breastfeed beyond six months may increase IQ in girls and decrease the incidence of childhood leukemia.12
One further potential consequence of cannabis consumption that is not attributed to breastfeeding is exposure to secondhand smoke. THC is detectable in bodily fluids of the exposed mother, and there’s a possible risk of sudden infant death in babies exposed to cannabis through paternal smoking.4
An increasing number of health care providers and cannabis coaches are comfortable with their patient’s use of cannabis while breastfeeding as part of a holistic care routine. While some cannabis coaches have professional credentials, there’s a growing movement of those with no health care background condoning the use of cannabis during lactation. Most health care providers, however, discourage cannabis use in breastfeeding mothers. There simply is not enough high-quality, robust evidence to indicate otherwise. Windi Muraszka, CNM, NP, MS, an OB/GYN nurse practitioner with a master’s degree in medical cannabis science and therapeutics, does not recommend cannabis product use during pregnancy or lactation. “But,” she says,” if someone is already using cannabis in pregnancy, I recommend decreasing the use and weaning off it until they are no longer pregnant or lactating. If they are not willing to do that, then I recommend decreasing the THC content to less than 20% volume and increasing the CBD content until it is as close to type 2 cannabis with 1:1 THC:CBD as possible to ameliorate the potential negative THC effects.” Ultimately, it’s a personal decision that each new mother must make in conjunction with her health care provider, and in certain circumstances it can be a viable option.
— Faye Berger Mitchell, MS, RDN, LDN, recently earned her MS degree in medical cannabis science and therapeutics from the University of Maryland School of Pharmacy, the only higher education medical cannabis program in the country. A registered and licensed dietitian, she combines her unique specialties in nutrition and medical cannabis, along with the skills and knowledge she acquired in her nutrition private practice and consulting career, to bring cutting edge information through her writing, individual coaching, speaking, and educational events to patients, allied health providers, and consumers.
Cannabis Use During Pregnancy
The primary concern regarding cannabis use during pregnancy is safety. While cannabis use by humans has been documented for at least 4,000 years for nausea, vomiting, pain, sleeplessness, depression, and anxiety, available studies are limited in quantity and quality. Clinicians must rely on a few case-control and cohort studies, along with anecdotal, retrospective, and qualitative studies. These studies suggest a possible correlation of cannabis use during pregnancy with low birth weight, increased risk of prematurity, and admission to the neonatal ICU.3,7 In other findings, cannabis exposure has been associated with developmental delays in fine motor and social skills in newborns. In addition, longitudinal studies in children of mothers who smoked cannabis during pregnancy found developmental issues extending past the neonatal period, including increased hyperactivity and impulsivity, memory dysfunction, decreased IQ scores, and even delinquent behavior.2
While it’s well established that the endocannabinoid system plays a role in the gestational cycle, the exact pharmacokinetic effects are not clearly understood. CB1 receptors present in the placenta are thought to be involved in regulation of serotonin transporter activity. It’s been hypothesized that these receptors, also present in the hippocampus, play a functionally significant role in the newborn sucking reflex. THC might alter the function of the hippocampus and orbitofrontal cortex—parts of the brain that regulate memory and focus. The pharmacokinetics are variable based on dosage and delivery method. However, once THC reaches the bloodstream, its highly lipophilic nature allows it to easily cross the placenta into the fetus.2
Given the lack of robust studies that provide conflicting data, professionals discourage cannabis use by nursing mothers. On the other hand, due to conflicting information and newer studies indicating less harm than once thought, a growing number of health care professionals are advising patients on a case-by-case basis.
1. Graves L. Cannabis and breastfeeding. Paediatr Child Health. 2020;25(Suppl 1):S26-S28.
2. Martin GI. Marijuana: the effects on pregnancy, the fetus, and the newborn. J Perinatol. 2020;40(10):1470-1476.
3. American College of Obstetrics and Gynecology. Committee opinion no. 722: marijuana use during pregnancy and lactation. Obstet Gynecol. 2017;130(4):e205-e209.
4. Joseph P, Vettraino IM. Cannabis in pregnancy and lactation - a review. Mo Med. 2020;117(5):400-405.
5. Navarrete F, García-Gutiérrez MS, Gasparyan A, Austrich-Olivares A, Femenía T, Manzanares J. Cannabis use in pregnant and breastfeeding women: behavioral and neurobiological consequences. Front Psychiatry. 2020;11:586447.
6. Is it safe for mothers who use marijuana to breastfeed? Centers for Disease Control and Prevention website. www.cdc.gov/breastfeeding/breastfeeding-special-circumstances/vaccinations-medications-drugs/marijuana.html. Published August 10, 2021. Accessed September 13, 2022.
7. Wang GS. Pediatric concerns due to expanded cannabis use: unintended consequences of legalization. J Med Toxicol. 2017;13(1):99-105.
8. Cannabis and breastfeeding. MGH Center for Women’s Mental Health website. https://womensmentalhealth.org/posts/cannabis-and-breastfeeding. Published November 26, 2019. Accessed September 8, 2022.
9. Cannabis. In: Drugs and Lactation Database (LactMed) [Internet]. Bethesda, MD: National Library of Medicine; 2006. https://www.ncbi.nlm.nih.gov/sites/books/NBK501587/. Updated June 20, 2022.
10. Monfort A, Ferreira E, Leclair G, Lodygensky GA. Pharmacokinetics of cannabis and its derivatives in animals and humans during pregnancy and breastfeeding. Front Pharmacol. 2022;13:919630.
11. Badowski S, Smith G. Cannabis use during pregnancy and postpartum. Can Fam Physician. 2020;66(2):98-103.
12. Williams PP, Washio Y, Myers B, et al. Cannabis use and breastfeeding: do we know enough? S Afr J Psychol. 2020;50(1):7-10.