Original Contribution Fetal Growth and Acute Childhood Leukemia: Looking Beyond Birth Weight

The authors examined the relation between birth weight, intrauterine growth, and risk of childhood leukemia using population-based linked health data from Western Australia. A cohort of 576,593 infants born in 1980–2004 were followed from birth to diagnosis of acute lymphoblastic leukemia (ALL) (n 243) or acute myeloid leukemia (AML) (n 36) before their 15th birthday, death, or the end of follow-up (December 31, 2005). Data were analyzed using Cox regression. Risk of ALL was positively associated with the proportion of optimal birth weight—ameasure of the appropriateness of fetal growth—particularly among children younger than 5 years; the hazard ratio for a 1-standard-deviation increase in proportion of optimal birth weight was 1.25 (95 % confidence interval: 1.07, 1.47). Among children younger than 5 years not classified as having high birth weight (defined as>3,500 g,>3,800 g, and>4,000 g), a 1-unit increase in proportion of optimal birth weight was associated with an approximately 40% increase in ALL risk. This suggests that accelerated growth, rather than high birth weight per se, is involved in the etiology of ALL. These findings are consistent with a role for insulin-like growth factor I in the causal pathway. Findings for AML were inconclusive, probably because of small numbers. birth weight; fetal development; leukemia; medical record linkage; proportional hazards models; risk factors Abbreviations: ALL, acute lymphoblastic leukemia; AML, acute myeloid leukemia; CI, confidence interval; IGF-I, insulin-like growth factor I