A new study has found that tetrahydrocannabinol (THC) from marijuana can linger in breast milk for up to six weeks after ceasing marijuana use.
Marijuana is the most commonly used dependent substance in pregnancy, with up to half of users continuing through pregnancy. The use of marijuana through pregnancy is likely due to its perceived safety as well as THC readily crosses the placental barrier, and cannabinoid receptors have been identified in both the placenta and the foetus. However, most studies done on marijuana and pregnancy dates from the 1980s – this study is the first of its kind to examine the levels of THC in breast milk since one in 1982.
“With the increasing utilisation of marijuana in society as a whole, we are seeing more mothers who use marijuana during pregnancy,” said primary investigator Erica Wymore, MD, MPH, Neonatologist, Children’s Colorado and Assistant Professor of Pediatrics, University of Colorado School of Medicine. “However, given the lack of scientific data regarding how long THC persists in breast milk, it was challenging to provide mothers with a definitive answer regarding the safety of using marijuana while breastfeeding and simply ‘pumping and dumping’ until THC was no longer detectable in their milk. With this study, we aimed to better understand this question by determining the amount and duration of THC excretion in breast milk among women with known prenatal marijuana use.”
The researchers screened women at the Children’s Colorado and UC Health’s University of Colorado Hospital for reported marijuana use or detected THC, who were willing to abstain from marijuana for the six week duration of the study. Of the 394 women screened, 25 enrolled in the study. Seven of these women were able to abstain from their marijuana use, while the others were not able to due depending on it for stress, sleep, and pain relief.
“This study provided invaluable insight into the length of time it takes a woman to metabolise the THC in her body after birth, but it also helped us understand why mothers use marijuana in the first place,” said Maya Bunik, MD, MPH, senior investigator, medical director of the Child Health Clinic and the Breastfeeding Management Clinic at Children’s Colorado and professor of pediatrics at the CU School of Medicine. “To limit the unknown THC effects on foetal brain development and promote safe breastfeeding, it is critical to emphasise marijuana abstention both early in pregnancy and postpartum. To help encourage successful abstention, we need to look at – and improve – the system of supports we offer new moms.”
While the study was not about the impact of maternal marijuana use on childhood development, longitudinal studies dating from the 1980s show that for children born to mothers who smoked marijuana during pregnancy, there are long-term issues with cognitive and executive functioning, including impulsivity, as well as deficits in learning, sustained attention and visual problem-solving skills. One recent retrospective study has also linked marijuana use in pregnancy to autism in children. Dr Wymore points out that this is cause for concern as currently available marijuana has a potency five to six times greater than what was available prior to legalisation.
Source: News-Medical.Net
Journal information: Wymore, E.M., et al. (2021) Persistence of Δ-9-Tetrahydrocannabinol in Human Breast Milk. JAMA Pediatrics. doi.org/10.1001/jamapediatrics.2020.6098.
