PRENATAL AND NEONATAL RISK-FACTORS FOR CHILDHOOD LYMPHATIC-LEUKEMIA

Background: Because the incidence of childhood acute lymphatic leukemi a peaks between 2 and 4 years of age, the risk factors may exert their influence during the prenatal and/or the neonatal periods. Results of previous studies of perinatal risk factors have been contradictory, p erhaps because most studies either have been hospital based or have be en restricted to limited geographical areas. Purpose: A nationwide cas e-control study was carried out to identify maternal and perinatal ris k factors for this disease. Methods: The case-control study was nested in cohorts defined by all live births in Sweden recorded in the natio nwide Medical Birth Register. Since 1973, this register has routinely collected information on all hospital births in regard to maternal dem ographic data, reproductive history, pregnancy, delivery, and the neon atal period. From the Swedish National Cancer Register, 613 case subje cts were identified in successive birth cohorts from 1973 through 1989 . Five control subjects per case subject were randomly selected from t he pool of children matched by sex and month and year of birth, Condit ional logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for potential risk factors and to e stimate their effects after adjustment for possible confounders. Resul ts: Risk of childhood lymphatic leukemia at all ages increased with Do wn's syndrome (OR = 20.0; 95% CI = 4.2-94.2), maternal renal disease ( OR = 4.4; 95% CI = 1.6-12.1), use of supplementary oxygen (OR = 23; 95 % CI = 1.5-3.6), postpartum asphyxia (OR = 1.8; 95% CI = 1.2-2.6), bir th weight of more than 4500 g (OR = 1.7; 95% CI = 1.1-2.7), and hypert ensive disease during pregnancy (OR = 1.4; 95% CI = 1.0-1.9). Down's s yndrome affected risk mostly in children younger than 5 years, whereas other factors affected those children 5 years old or older. Being one of a multiple birth also increased risk among older children (OR = 2. 5; 95% CI = 1.0-6.0). Use of supplementary oxygen may act as a causal intermediate (surrogate) for postpartum asphyxia and its causes, as wo uld high birth weight for its causes. Conclusions: Several maternal an d perinatal risk factors were found to be associated with childhood ly mphatic leukemia, but they showed age-specific differences, Overall, o nly a few risk factors were identified, and these accounted for a smal l proportion of cases, We concluded that most risk factors for childho od lymphatic leukemia remain unidentified in very young children.