Cannabis in pregnancy
Cannabis consumption in pregnancy might be associated with restrictions in growth of the fetus, miscarriage, and cognitive deficits in offspring based on animal studies, however there is limited evidence for this in humans at this time. The American Congress of Obstetricians and Gynecologists recommended that cannabis use be stopped before and during pregnancy.
Although it is difficult to draw firm conclusions, there is some evidence that prenatal exposure to marijuana is associated with deficits in language, attention, cognitive performance, and delinquent behaviors. THC exposure in rats during the prenatal developmental phase may cause epigenetic changes in gene expression, but there is limited knowledge about the risk for psychiatric disorders because of ethical barriers to studying the developing human brain. While animal studies cannot take into account factors that could influence the effects of cannabis on human maternal exposure, such as environmental and social factors, a 2011 review of rodent studies by Campolongo et al. said there was "... increasing evidence from animal studies showing that cannabinoid drugs ... induce enduring neurobehavioral abnormalities in the exposed offspring ..." Campolongo et al. added that "clinical studies report hyperactivity, cognitive impairments and altered emotionality in humans exposed in utero to cannabis".
A role in female fertility has long been suspected and studied. Most studies through 2013 linking development of the fetus and cannabis show effects of consumption during the gestational period, but problems in the endocannabinoid system (ECS) during the phase of placental development are also linked with problems in pregnancy. According to Sun and Dey (2012), endocannabinoid signaling plays a role in "female reproductive events, including preimplantation embryo development, oviductal embryo transport, embryo implantation, placentation, and parturition". Karusu et al (2011) said that a "clear correlation ... in the actual reproductive tissues of miscarrying versus healthy women has yet to be established. However, the adverse effects of marijuana smoke and THC on reproductive functions point to processes that are modulated by ECS."
Keimpema and colleagues (2011) said, "Prenatal cannabis exposure can lead to growth defects during formation of the nervous system"; "[c]annabis impacts the formation and functions of neuronal circuitries by targeting cannabinoid receptors ... By indiscriminately prolonging the "switched-on" period of cannabinoid receptors, cannabis can hijack endocannabinoid signals to evoke molecular rearrangements, leading to the erroneous wiring of neuronal networks". A report prepared for the Australian National Council on Drugs concluded cannabis and other cannabinoids are contraindicated in pregnancy as they may interact with the endocannabinoid system.
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- Committee on Obstetric Practice (July 2015). "Committee Opinion No. 637: Marijuana Use During Pregnancy and Lactation". Obstetrics & Gynecology: 126 (1): 234–238. doi:10.1097/01.AOG.0000467192.89321.a6.
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- Jutras-Aswad D, DiNieri JA, Harkany T, Hurd YL (October 2009). "Neurobiological consequences of maternal cannabis on human fetal development and its neuropsychiatric outcome". Eur Arch Psychiatry Clin Neurosci (Review) 259 (7): 395–412. doi:10.1007/s00406-009-0027-z. PMID 19568685.