PRENATAL AND NEONATAL RISK-FACTORS FOR CHILDHOOD MYELOID-LEUKEMIA

Information about the etiology of childhood myeloid leukemia is limite d, A population-based nested case-control study of prenatal and neonat al risk factors for childhood myeloid leukemia was performed with the use of the Swedish National Cancer Register and the Swedish Birth Regi ster, A total of 98 cases of myeloid leukemia were identified in succe ssive birth cohorts from 1973 through 1989, From the Birth Register, f ive controls were matched to each case. Fourteen of the 98 cases with myeloid leukemia and none of the controls had Down syndrome [odds rati o (OR) = infinity; 95% confidence interval (CI) = 21.0-infinity]. The risk for myeloid leukemia also increased among children who had physio logical jaundice (OR = 2.5; 95% CI = 1.2-5.0); children who had been t reated with phototherapy (OR = 7.5; 95% CI = 1.8-31.9); or who had bee n treated in an incubator (OR = 3.5; 95% CI = 1.2-10.2). Excluding cas es with Down syndrome, however, decreased these risks, so that their 9 5% lower confidence interval included the no-effect value, Maternal ag e <20 years old (OR = 2.5; 95% CI = 1.1-6.0), hypertension (OR = 2.4; 95% CI = 1.2-5.0), Cesarean section (OR = 2.5; 95% CI = 1.3-4.9), mate rnal smoking (OR = 2.4; 95% CI = 0.9-6.5), and being one of a multiple birth (OR = 3.6; 95% CI = 1.1-11.3) increased the risk for myeloid le ukemia among those without Down syndrome, When the analyses were repea ted, by restricting the cases to those with acute myeloid leukemia, th e risk associated with young maternal age declined and became nonsigni ficant. Down syndrome is markedly associated with increased risk of my eloid leukemia, Because Down syndrome is underreported in the Birth Re gister. Down syndrome may give rise to some residual confounding, ther eby accounting for some of the other associations obtained, Besides Do wn syndrome, the other medical condition or factors linked with increa sed risk of myeloid leukemia, need additional confirmation.