Perinatal risk factors for the onset of bipolar disorder in young adulthood: a 22-year birth cohort.

Objective: Bipolar disorder (BD) is a major cause of disability-adjusted life years in young adults. Pregnancy complications have previously been associated with BD. The current study aimed to examine the association between perinatal factors and BD.

Methods: We included 3,794 subjects from the 1993 Pelotas population-based birth cohort study. We assessed 27 variables at birth and modeled BD onset at 18 and 22 years. Bivariate analysis was performed by means of binomial logistic regression models. The variables with p-values less than 0.05 were included in a multiple regression with confounders.

Results: Maternal smoking was associated with a 1.42-fold increased risk of BD at 18 or 22 years old (95%CI 1.091-1.841), and maternal passive exposure to tobacco with a 1.43-fold increased risk (95%CI 1.086-1.875). No association was found between other perinatal factors and BD after controlling for confounders.

Conclusion: The results of the present cohort study corroborate previous reports in the literature indicating a negative effects of maternal smoking during pregnancy. These findings can be further tested and support the development of strategies to prevent the onset development of BD.