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To the Editor: Approximately 40% to 50% of all human conceptions are lost before 20 weeks of gestation.¹ Recent animal studies suggest that the endocannabinoid anandamide (N-arachidonoyl-ethanolamine) is critical for both the synchronous development of the blastocyst and the endometrium in preparation for implantation, with low anandamide levels essential for successful implantation.² Plasma anandamide levels are regulated by fatty acid amide hydrolase (FAAH), the enzyme (up-regulated by progesterone) that metabolizes anandamide into arachidonic acid and ethanolamine.³ Increased FAAH expression and lower anandamide levels have been demonstrated at the implantation site and low FAAH expression and high anandamide levels at the interimplantation site prior to successful implantation.² Levels of FAAH in peripheral blood mononuclear cells from uncomplicated early pregnancies were significantly lower in women who subsequently miscarried.⁴ In women undergoing in vitro fertilization and embryo transfer, high plasma anandamide level at 6 weeks after embryo transfer was associated with . . . [Full Text of this Article]

Methods

Osama M. H. Habayeb, MBBS; Anthony H. Taylor, PhD; Mark Finney, MBchB
Reproductive Sciences Section

Mark D. Evans, PhD
Radiation and Oxidative Stress Group

Justin C. Konje, MD
jck4@le.ac.uk
Endocannabinoid Research Group
Reproductive Sciences Section
Department of Cancer Studies and Molecular Medicine
University of Leicester
Leicester Royal Infirmary
Leicester, Leicestershire, United Kingdom