Chapel Hill, NC: Marijuana use by mothers is not associated with an increased risk of childhood acute myeloid leukemia (AML) in offspring, according to a case-control study to be published in the March issue of the journal Pediatric and Perinatal Epidemiology.
Researchers at the University of North Carolina at Chapel Hill analyzed 517 cases of children with AML and 610 unmatched controls. Incident cases were defined as children less than 18 years of age who had been diagnosed with AML between 1989 and 1993, and were registered with the Children's Cancer Group (a pediatric clinical co-operative group). Control children were selected via random digit dialing and individually matched.
"Overall, no positive associations between parental marijuana use and childhood AML were observed," investigators found. In addition, researchers found that self-reported maternal marijuana use "in the 3 months before, or during pregnancy was associated with a decreased [risk] of childhood AML."
They added: "Some evidence of a dose-response relationship was observed with those reporting use once or more per week in the 3 months before pregnancy having a more reduced odds ratio than those reporting less than once per week. Decreased odds ratios were also noted for maternal marijuana smoking in the year after birth."
Investigators did not conclude, however, that maternal marijuana use could protect against AML. Rather, they suggested that the inverse association may be the result of "recall bias" (e.g., case mothers may have been less likely than control mothers to report having used marijuana before or during pregnancy).
The study's results contradict the findings of a 1999 investigation that did note an association between maternal cannabis use and childhood AML.
"The previously reported positive association between maternal marijuana use before or during pregnancy and childhood AML was not confirmed in this study," investigators concluded. "Parental marijuana use is unlikely as a strong risk factor for childhood AML."
The UNC study is the largest epidemiological study of childhood AML to date in the United States.
Acute myeloid leukemia comprises approximately 16 percent of leukemias diagnosed in individuals younger than 15 years of age.
For more information, please contact Paul Armentano, NORML Senior Policy Analyst, at (202) 483-5500. Full text of the study, "Parental marijuana use and risk of childhood acute myeloid leukaemia: a report from the Children's Cancer Group," appears in the March issue of the journal Pediatric and Perinatal Epidemiology.