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Although previous polio infection remains a considerable cause of long-term morbidity worldwide, few studies have examined the psychiatric consequences of poliomyelitis. The authors followed 4,660 polio patients hospitalized at the primary infectious disease hospital in Copenhagen, Denmark, between 1922 and 1954 as well as 19,017 age- and gender-matched Danes for psychiatric hospitalizations from January 1, 1977, to December 31, 1993. Incidence rates of all psychiatric disorders combined and of separate diagnostic groups of psychiatric diseases in the two cohorts were compared, yielding the incidence rate ratio, a measure of relative risk. Overall, polio patients had a 40% increased risk of being hospitalized for a psychiatric disorder (incidence rate ratio = 1.43, 95% confidence interval: 1.23, 1.66). Apparently, the overall increased risk of psychiatric hospitalizations could not be confined to specific groups of psychiatric disorders but seemed to be explained by slightly increased risks of several different disorders, especially milder psychiatric disorders. Finally, psychiatric morbidity did not differ between paralytic and nonparalytic polio patients. History of hospitalization for polio might be associated with subsequent risk of hospitalization for psychiatric disorders. The underlying mechanism for this association remains uncertain. [ABSTRACT FROM AUTHOR]

Evidence has emerged that childhood leukemia is initiated in utero. High birth weight is one of the few birth-related factors that has been associated with childhood leukemia, albeit not consistently. The authors conducted a meta-analysis of studies of the association between birth weight and childhood leukemia risk. Study-specific odds ratios for leukemia were calculated, using a cutoff at 4,000 g of birth weight. The authors also evaluated whether the association between birth weight and leukemia followed a log-linear dose-response-like pattern. They calculated summary estimates using weighted averages of study-specific odds ratios from dichotomous and trend analyses. Eighteen studies (published between 1962 and 2002) were included, encompassing 10,282 children with leukemia. Children weighing 4,000 g or more at birth were at higher risk of acute lymphoblastic leukemia than children weighing less (odds ratio (OR) = 1.26, 95% confidence interval (CI): 1.17, 1.37). Furthermore, data were consistent with a dose-response-like effect (OR = 1.14/1,000-g birth weight increase, 95% CI: 1.08, 1.20). Studies of acute myeloid leukemia indicated a similar increase in risk for children weighing 4,000 g or more at birth (OR = 1.27, 95% CI: 0.73, 2.20) and a dose-response-like effect (OR = 1.29/1,000 g, 95% CI: 0.80, 2.06), but results varied across studies. Our findings support a relation between birth weight and childhood acute lymphoblastic leukemia risk and emphasize the need for additional studies of the biologic mechanisms underlying this association. [ABSTRACT FROM AUTHOR]