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

Background: Bipolar disorder (BD) is a leading cause of disability-adjusted life years in young adults. Complications during prenatal periods have been associated with BD previously. The study aims to examine the association between perinatal factors and BD in order to prevent the risk of developing BD.

Methods: 3,794 subjects from the 1993 Pelotas population-based birth cohort study were included. We assessed 27 initial variables at birth and modelled BD onset at 18 and 22 years. We performed bivariate analysis, using binomial logistic regression models. The variables with p-value smaller than 0.05 were included into a multiple regression with confounding variables.

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 confounding factors.

Conclusion: The results of this cohort corroborate with previous findings in the literature that already indicate the negative outcomes of maternal smoking during pregnancy. They may now be linked to other studies to target these factors for preventing the development of BD.