Women who continued to use cannabis during pregnancy often perceived no general or pregnancy-specific risk compared to nonusers and rarely receive counseling regarding their marijuana use from healthcare providers1.
However, cannabis is able to freely cross the placenta during pregnancy, making marijuana use during pregnancy an important issue that may affect the health of both pregnant women and their offspring. Neonates exposed to marijuana in utero are at risk of low birth weight and are more likely to need placement in the neonatal intensive care unit2.
In animal models, high doses of cannabis cause growth retardation and malformations in offspring3. It is thought that cannabis exposure may impact human fetus neurodevelopment, especially executive functioning and memory, but findings have been inconsistent and more investigation is necessary.
Marijuana use while breastfeeding may also pose harm to newborns as cannabinoids appear in breast milk at an estimated 0.8 to 2.5% of maternal exposure. It is estimated that 84% of cannabis users during pregnancy continued use during lactation4, and one U.S. survey indicated that approximately 15% of breastfeeding mothers reported past year cannabis use5.
The impact of the marijuana exposure specifically on the newborn is unknown, in part due to the substantial overlap between women who use marijuana during pregnancy and during the lactation period. Marijuana may also impact a woman’s ability to lactate altogether, as there is some evidence that cannabis may inhibit prolactin secretion, the key neuroendocrine mediator of lactation.
Men seeking to impregnate must also be cautious of cannabis use. Marijuana use can disrupt the signaling pathways in the male reproductive process. Both in vitro and in vivo studies suggest that cannabis disrupts the hypothalamic-pituitary axis, reduces spermatogenesis, and impairs sperm function by disrupting motility, capacitation, and the acrosome reaction. These disruptions can lead to impaired reproductive potential or even infertility6.
Some research has even suggested that heavy paternal cannabis use can lead to behavioral changes in their offspring through epigenetic changes. In murine models, offspring of rats exposed to high levels of THC had poor attention performance and impaired stress responses7. Further research on the topic in human studies is necessary.