Obstetric history and birth characteristics and Wilms tumor: a report from the Children's Oncology Group.

Previous epidemiologic studies have suggested that various pregnancy and birth characteristics may be associated with Wilms tumor, a childhood kidney tumor. We evaluated obstetric events and birth characteristics in relation to Wilms tumor using data from a large North American case-control study. Mothers of 521 children with Wilms tumor and 517 controls, frequency matched on child's age and geographic region, provided information about their labor and delivery history and their children's birth characteristics through a detailed computer-assisted telephone interviews. Most obstetric factors were not associated with Wilms tumor, but modest associations were observed for labor induction (OR: 1.4, 95% Confidence Interval (CI): 1.1, 1.8), prenatal vaginal infection (OR: 1.8, 95% CI: 1.2, 2.8), and upper respiratory infection (OR: 1.5, 95% CI: 1.0, 2.4). Low (<2500 g) and high (>4500 g) birth weight and preterm delivery (<37 weeks completed gestation) were associated with an elevated risk of Wilms tumor, as was neonatal respiratory problems. The association for high birth weight was present only among children with perilobar nephrogenic rests (OR: 2.1, 95% CI: 1.2, 3.9), possibly distinguishing a specific association among a biologically distinct subgroup of Wilms tumor cases. The results of this large study did not support many of the earlier findings of smaller studies. However, additional investigations of the effects of certain obstetric and birth characteristics among more refined tumor subgroups may further our understanding of these factors in relation to Wilms tumor.