Preterm birth and psychiatric medication prescription in young adulthood: a Swedish national cohort study.

BACKGROUND Recent studies suggest an increased risk of adverse mental health outcomes among young adults who were born preterm. These studies have been based mainly on hospital data, thus missing large numbers of mental health problems that do not require inpatient treatment. We used national outpatient and inpatient pharmacy data to evaluate whether individuals who were born preterm were more likely to be prescribed psychiatric medications during young adulthood than individuals who were born full term. METHODS A national cohort of all infants born in Sweden from 1973 through 1979 [N = 635,933, including 28,799 who were born preterm (<37 weeks)] was followed to ages 25.5-34.0 years to determine whether psychotropic medications (antidepressants, antipsychotics, anxiolytics, hypnotics/sedatives and/or psychostimulants) were prescribed in 2005-06. RESULTS A trend of increasing rate of prescriptions for antipsychotics, antidepressants and hypnotics/sedatives in young adulthood was observed by earlier gestational age at birth. Young adults who were extremely preterm at birth (23-27 weeks) were 3.1 times more likely to be prescribed antipsychotics [95% confidence interval (CI) 1.66-5.93], 1.8 times more likely to be prescribed antidepressants (95% CI 1.26-2.64) and 1.8 times more likely to be prescribed hypnotics/sedatives (95% CI 1.15-2.96) than individuals who were full term at birth, after adjusting for potential confounders. CONCLUSIONS This national cohort study, using outpatient and inpatient pharmacy data, suggests that preterm birth has important independent effects on mental health that extend at least into young adulthood.