Use of Medication during Pregnancy and Risk of Childhood Leukemia (Canada)

Objective: To examine risk of childhood acute lymphoblastic leukemia (ALL) associated with maternal use of medications during pregnancy; in particular medications known or suspected to be teratogenic. Methods: Seven hundred and eighty nine children (< 15 years old) diagnosed with ALL in the province of Québec between 1980 and 2000 were recruited for study. A similar number of population based controls matched to cases (1:1) by sex and age were chosen from family allowance or health insurance files. Information was gathered via telephone interview with the subjects' parents. Data were analyzed using conditional logistic regression. Results: Risk of childhood ALL was significantly increased in the offspring of mothers who reported using any medication (adjusted odds ratio (ORadj) = 1.3, 95% CI = 1.0-1.6) or any teratogenic medication (ORadj= 1.4, 95% CI = 1.1-1.9) during pregnancy. Among specific medication categories, only central nervous system depressants were associated with a significantly increased risk, although elevated odd ratios were found for anti-epileptics, immunosuppressants, oral contraceptives, and illicit drugs. Risk associated with use of teratogenic medications was higher with increased dose and in children diagnosed before two years of age. Conclusion: A modest increase in risk of ALL was found among children of mothers who used medication during pregnancy.