Human ReproductionWomen who use marijuana could have a more difficult time conceiving a child than women who do not use marijuana, suggests a study by researchers at the National Institutes of Health. Marijuana use among the women’s partners—which could have influenced conception rates—was not studied. The researchers were led by Sunni L. Mumford, Ph.D., of the Epidemiology Branch in NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development. The study appears in Human Reproduction.