Marihuana, Marijuana

Hemp (Cannabis sativa), is a plant rich in cannabinoids, the main one being Δ9-TetraHydroCannabinol (THC) which has psychotropic properties. Other cannabinoids, which lack psychoactive effects are cannabidiol (CBD), cannabigerol, cannabinol and Δ8-tetrahydrocannabinol ^{(ElSohly 2017)}. It also contains numerous flavonoids, phytosterols, vitamins, fatty acids, amino acids, proteins, enzymes, sugars, alkaloids and essential oil, among others. Cannabis preparations can be taken orally, inhaled by vaporization, topically or in rectal suppositories.

Cannabis oil is a resinous substance extracted from the Cannabis plant (sativa or indica). It contains the plant’s main cannabinoids, including THC and CBD. Depending on the method of extraction or manufacture of cannabis oil, it may contain more or less THC. There are several CBD-based medicines that contain varying amounts of THC, for the treatment of vomiting during anti-cancer treatments and to treat pain, spasticity or epilepsy in certain diseases. The proportion of THC in the various products derived from marijuana has been progressively increasing over the last few years. ^{(Metz 2015)}

Delta-9-TetraHydroCanabinol (THC) is highly lipophilic, accumulates in fatty tissues such as the brain (Ryan 2018) and reaches up to 8.4 times the plasma concentration in breastmilk. ^{(Pérez 1982)}

THC is excreted in breast milk in small quantities, but could be significant (RD up to 8.7%) as it is a psychotropic drug; CBD is excreted in very small amounts ^{(Moss 2021, Bertrand 2018, Baker 2018, Marchei 2011)}.

Although mean plasma elimination times (T_1/2) of between 25 and 57 hours have been described (Hale), a recent work estimated the T_1/2 in breast milk at 11.5 hours. The peak concentration (T _max) in breast milk was between 0.5 and 2 hours. ^{(Holdsworth 2024)}

THC is detected in breastmilk up to 3 to 6 weeks after its last use ^{(Wymore 2021 & 2018)}. THC has been found in much higher quantities than expected in faeces of infants whose mothers smoked marijuana, suggesting subsequent absorption and metabolization: marijuana is excreted mainly by faeces. ^{(Pérez 1982)}

A 6-month-old infant exclusively breastfed by a mother who was a chronic cannabis user was hospitalized for accidental head injury and excessive sleepiness. He had high THC values in blood and urine up to 36 hours after admission. ^{(Mabey 2022)}

A 5-week-old breastfed infant presented with recurrent apnea episodes and a positive urine delta-9-tetrahydrocannabinol (THC) screening test. The mother used cannabis regularly for the treatment of depression and anxiety during pregnancy and breastfeeding. ^{(Kaplan 2024)}

Cannabis consumption may decrease milk production and slightly alter macronutrient composition (more lactose and protein). ^{(Josan 2023)}

Cannabinoids, mainly THC, can disrupt normal axonal growth in developing brains ^{(Tortoriello 2014)}. The body's endocannabinoid system has a key role in brain development during pregnancy, breastfeeding and adolescence and is affected by the external input of THC, so exposure to THC during pregnancy and breastfeeding is of concern, since it can cause epigenetic changes in brain development. ^{(Henschke 2019, Sachs 2013, Campolongo 2009, Fernández 2004)}

There are few studies about the effects of maternal cannabis use on breastfed infants and it is difficult to separate them from use during pregnancy:

• A link has been found between exposure during the prenatal period and breastfeeding and neurodevelopmental delay, cognitive deficit, behavioural alterations (including criminal behaviour), drug use and attention deficit disorder in childhood and adolescence. ^{(Smith 2016, Tortoriello 2014, Sharma 2012, Goldschmidt 2012 and 2008, Jaques 2005, Fried 2001 and 1995, Day 2011, 2006 and 1994)}
• Two studies found no delay in short- to medium-term growth or psychomotor development in infants of mothers who smoke marijuana. ^{(Ilett 2012, Tennes 1985)}
• One study found motor delay at one year of age in infants of mothers who smoked marijuana; the delay was dose-dependent: the delay is greater the more they smoked and is also greater if they did so during the first month. ^{(Moretti 2000, Astley 1990)}

Maternal cannabis use during pregnancy is related to lower birth weight and head circumference ^{(El Marroun 2009, Fergusson 2002, Fried 1999)}. Paternal marijuana use was associated with an increased risk of sudden infant death. ^{(Klonoff 2001)}

Cannabis use is associated with increased cortisol levels and decreased prolactin levels ^{(Ranganathan 2009, D'Souza 2008, Mendelson 1985)}; other authors have not found hormonal alterations. ^{(Block 1991)}

Cannabis use is associated with a shorter duration of breastfeeding ^{(Crume 2018. Ko 2018)}, increased tobacco use and postpartum depression ^{(Ko 2018)}. The alteration of judgment and behaviour and the greater frequency of mental disorders, including psychosis ^{(Starzer 2018, Vallersnes 2016, Volkow 2014, Moore 2007)} which cannabis use produces can interfere with the mother’s capacity for adequate care. ^{(Colorado DPHE 2017, Lawrence 2016 p604, Jansson 2015, ABM 2015, Jaques 2014, D'Souza 2008)}

Various medical associations, experts and expert consensus consider the use of cannabis, both recreationally and medicinally, to be contraindicated during pregnancy and breastfeeding. ^{(Adashi 2019, van den Elsen 2019, Thompson 2019, Hale 2019, Ryan 2018, Jansson 2018, Krening 2018, Metz 2018 and 2015, Obs-Gyn Committee 2017, Jansson 2015, Briggs 2015, Warner 2014, Rowe 2013, Garry 2009, Schaefer 2007)}

Other authors, given the risks of formula feeding and the lack of accurate data on the effects of cannabis on breastfeeding, choose to advise mothers not to give up its use, to continue breastfeeding and minimize cannabis use, avoid using it in the same room and monitor the possible effects on infants. ^{(Anderson 2017, ABM 2015, Djulus 2005)}

Until more information is published regarding breastfeeding and cannabis products for medicinal use, safer known pharmacological alternatives are preferable.

Mothers who breastfeed should be warned of the possible negative effects of THC on the brain and neurobehavioral development of their babies in the short and long term, and they should be advised to eliminate the use of marijuana in any form during breastfeeding. ^{(Wallman 2021)}

Sharing a bed with the baby is not recommended if this drug is being used due to an increased risk of suffocation or sudden infant death. ^{(UNICEF 2018, 2017, 2014 and 2013, Landa 2012, ABM 2008, UNICEF 2006)}

See below the information of these related products:

• Hemp (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)
• Maternal Drug Addiction (Very unsafe. Contraindicated. Use of an alternative or cessation of breastfeeding. Read the Commentary.)