Prenatal exposure to maternal bereavement and offspring psoriasis: a Danish nationwide cohort study

Background Prenatal stress may alter immune competence of the fetus. Limited data exist on the role of antenatal stress in psoriasis development. Objectives To investigate whether prenatal exposure to maternal bereavement increases the risk of offspring psoriasis. Methods This register-based cohort study included 1 811 917 live singletons born from 1978 to 2008 in Denmark. The children were assigned to the bereaved group if their mothers lost a child, partner/spouse, parent or sibling during pregnancy or up to 12 months before pregnancy. Follow-up started at the date of birth and ended at the date of first hospital treatment for psoriasis or a prescription redeemed for topical vitamin D derivatives (often used to treat psoriasis), emigration, death or 31 December 2010, whichever came first. We evaluated the hazard ratio (HR) of psoriasis in bereaved children using Cox proportional hazards regressions, compared with the nonbereaved group. Results During 28 million person-years of follow-up, 7956 children were hospitalized or prescribed medications for psoriasis. By the age of 30 years, 1.54% [95% confidence interval (CI) 1.25-1.90%] of children from the bereaved group were diagnosed with psoriasis, compared with 1.34% (95% CI 1.30-1.38%) of nonbereaved children. Overall, prenatal exposure to maternal bereavement was not associated with risk of psoriasis in general (HR 1.05, 95% CI 0.91-1.20). However, children born to mothers who lost a partner/spouse or an older child had an increased risk of psoriasis (HR 1.33, 95% CI 1.02-1.73). Conclusions Prenatal exposure to the most stressful life event may contribute to the development and/or exacerbation of psoriasis.