An earlier meta-analysis of seven randomized controlled trials examining specifically the role of vitamin A supplementation in 2,069 children with measles found no overall reduction on the risk of mortality (72) . Yet, the pooled analysis of four studies that reported the age distribution of participants found an 83% lower risk of mortality with two doses of 200,000 IU of vitamin A in children younger than two years. In addition, the pooled analysis of three studies indicated a 67% reduction in the risk of pneumonia -led mortality (72) . Similar to WHO and UNICEF guidelines, the American Academy of Pediatrics recommends vitamin A supplementation for children over six months of age when they are infected with measles while malnourished, immunodeficient, or are at risk of measles complications or vitamin A deficiency disorders (73) . Although measles infection has been associated with vitamin A deficiency and blindness, there is currently no evidence to suggest that vitamin A supplementation reduces the risk of blindness in children infected with measles (74) .
Reproductive and Perinatal Effects
Basic science research outstrips clinical research in the complex area of the role endocannabinoids play in all aspects of human reproduction and the impact of exogenous cannabinoids (., the THC and other cannabinoid compounds in marijuana) on reproductive physiology. Animal studies have demonstrated the existence of CB1 receptors, endogenous cannabinoid ligands and the degradation by fatty acid amide hydrolase (FAAH) in sperm, eggs, and preimplantation embryos (Schuel 2006). Studies have found a critical balance between anandamide synthesis and its degradation by FAAH in mouse embryos and oviducts necessary for normal embryo development, oviductal transport, implantation and pregnancy (Wang, Guo et al. 2004; Wang, Xie et al. 2006). As a result, marijuana and THC have been shown in animal models to effect multiple aspects of reproductive physiology, including secretion of gonadotrphic hormones by the pituitary and sex steroids by the gonands, sperm production and capacitation, ovulation, fertilization, early embryonic devepoment, implantation, placental functions, fetal growth, number of pregnancies carried to term, lactation, suckling behavior by newborns and growth of malignant breast and prostate cells (Schuel 2006). The clinical implications of these basic science findings for human reproduction remains unclear despite the fact that animal studies show that exogenous THC can swamp endogenous anadamide signaling systems, thereby affecting multiple physiological processes.