Antenatal maternal bereavement and childhood cancer in the offspring: a population-based cohort study in 6 million children.

Background:Prenatal stress may increase the susceptibility to childhood cancer by affecting immune responses and hormonal balance. We examined whether antenatal stress following maternal bereavement increased the risk of childhood cancer.Methods:All children born in Denmark from 1968 to 2007 (N=2 743 560) and in Sweden from 1973 to 2006 (N=3 400 212) were included in this study. We compared cancer risks in children born to women who lost a first-degree relative (a child, spouse, a parent, or a sibling) the year before pregnancy or during pregnancy with cancer risks in children of women who did not experience such bereavement.Results:A total of 9795 childhood cancer cases were observed during follow-up of 68 360 707 person years. Children born to women who lost a child or a spouse, but not those who lost other relatives, had an average 30% increased risk of any cancer (hazard ratio (HR) 1.30, 95% confidence interval (CI) 0.96-1.77). The HRs were the highest for non-Hodgkin disease (512 cases in total, HR 3.40, 95% CI 1.51-7.65), hepatic cancer (125 cases in total, HR 5.51, 95% CI 1.34-22.64), and testicular cancer (86 cases in total, HR 8.52, 95% CI 2.03-37.73).Conclusion:Our data suggest that severe antenatal stress following maternal bereavement, especially due to loss of a child or a spouse, is associated with an increased risk of certain childhood cancers in the offspring, such as hepatic cancer and non-Hodgkin disease, but not with childhood cancer in general. [ABSTRACT FROM AUTHOR]