Prematurity and low birth weight as risk factors for the development of affective disorder, especially depression and schizophrenia: a register study.

Abstract

Larsen JK, Bendsen BB, Foldager L, Munk-Jørgensen P. Prematurity and low birth weight as risk factors for the development of affective disorder, especially depression and schizophrenia: a register study. The present study examined whether low birth weight, prematurity or low birth weight adjusted for gestational age are risk factors for the subsequent development of affective disorder, especially depression. A population-based case-control design was applied to the Danish Medical Birth Register and the Danish Psychiatric Central Register to identify all individuals born between 1 January 1974 and 31 December 1990 and diagnosed prior to 29 August 2003 with affective disorder alone (ICD-10 F3; 4297 females, 1861 males), schizophrenia alone (ICD-10 F2; 1364 females, 2292 males) or both disorders (ICD-10 F3 + F2; 450 females, 405 males). The association between low birth weight and the risk of developing affective disorder and/or schizophrenia was analysed by conditional logistic regression analysis. Low birth weight was found to be associated with a significantly elevated risk of developing schizophrenia alone (p = 0.021) and both affective disorder and schizophrenia (p = 0.024), and a non-significantly elevated risk of developing affective disorder alone (p = 0.063). The effect remained significant in the affective disorder and schizophrenia groups (p = 0.039) when correcting for gestational age (premature birth), but was lost in the group with both disorders. Premature birth per se was found to be associated with a significantly elevated risk of developing both affective disorder and schizophrenia (p = 0.00018), an effect that remained significant after adjustment for low birth weight. Prematurity and low birth weight were found to be risk factors for subsequent development of affective disorder (especially depression) and schizophrenia.