Objective: To investigate the risks of adverse pregnancy and birth outcomes for treated and untreated bipolar disorder during pregnancy.
Design: Population based cohort study using data from national health registers.
Setting: Sweden.
Participants: 332,137 women with a last menstrual period anytime after 1 July 2005 and giving birth anytime before the end of 31 December 2009. Women with a record of at least two bipolar diagnoses were identified and grouped as treated (n = 320)-those who had filled a prescription for mood stabilisers (lithium, antipsychotics, or anticonvulsants) during pregnancy-or untreated (n = 554). Both groups were compared with all other women giving birth (n = 331,263).
Main outcome measures: Preterm birth, mode of labour initiation, gestational diabetes, infants born small or large for gestational age, neonatal morbidity, and congenital malformations.
Results: Of the untreated women, 30.9% (n = 171) were induced or had a planned caesarean delivery compared with 20.7% (n = 68,533) without bipolar disorder (odds ratio 1.57, 95% confidence interval 1.30 to 1.90). The corresponding values for the treated women were 37.5% (n = 120) (2.12, 1.68 to 2.67). The risks of preterm birth in both treated and untreated women were increased by 50%. Of the untreated women, 3.9% (n = 542) had a microcephalic infant compared with 2.3% (324,844) of the women without bipolar disorder (1.68, 1.07 to 2.62). The corresponding values for the treated women were 3.3% (n = 311) (1.26, 0.67 to 2.37). Similar trends were observed for risks of infants being small for gestational age infants for weight and length. Among infants of untreated women, 4.3% (n = 24) had neonatal hypoglycaemia compared with 2.5% (n=8302) among infants of women without bipolar disorder (1.51, 1.04 to 2.43), and 3.4% (n = 11) of the treated women (1.18, 0.64 to 2.16). The analyses of variation in outcomes did not support any significant differences between treated and untreated women.
Conclusions: Bipolar disorder in women during pregnancy, whether treated or not, was associated with increased risks of adverse pregnancy outcomes.