Perinatal factors and the risk of bipolar disorder in Finland.
BACKGROUND
Complications during the perinatal period have been associated with neurodevelopmental disorders like schizophrenia and autism. However, similar studies on bipolar disorder (BPD) have been limited and the findings are inconsistent. The aim of this study was to examine the association between perinatal risk factors and BPD.


METHODS
This nested case-control study, based on the Finnish Prenatal Study of Bipolar Disorders (FIPS-B), identified 724 cases and 1419 matched controls from population based registers. Conditional logistic regression was used to examine the associations between perinatal factors and BPD adjusting for potential confounding due to maternal age, psychiatric history and educational level, place of birth, number of previous births and maternal smoking during pregnancy.


RESULTS
Children delivered by planned cesarean section had a 2.5-fold increased risk of BPD (95% CI: 1.32-4.78, P<0.01). No association was seen between other examined perinatal risk factors and BPD.


CONCLUSIONS
The limitations of this study include: the restriction in the sample to treated cases of BPD in the population, and usage of hospital based clinical diagnosis for case ascertainment. In addition, in spite of the large sample size, there was low power to detect associations for certain exposures including the lowest birth weight category and pre-term birth.


CONCLUSIONS
Birth by planned cesarean section was associated with risk of BPD, but most other perinatal risk factors examined in this study were not associated with BPD. Larger studies with greater statistical power to detect less common exposures and studies utilizing prospective biomarker-based exposures are necessary in the future.
Department of Child Psychiatry, University of Turku, Finland. Electronic address: roschu@utu.fi.
Roshan
R
Chudal
Department of Child Psychiatry, University of Turku, Finland; Department of Child Psychiatry, Turku University Hospital, Finland; Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York, NY, USA; Regional Centre for Child and Youth Mental Health and Child Welfare, University of Tromsø, Norway.
Andre
A
Sourander
Department of Obstetrics and Gynecology, Turku University Hospital and University of Turku, Turku, Finland.
Päivi
P
Polo-Kantola
Department of Child Psychiatry, University of Turku, Finland.
Susanna
S
Hinkka-Yli-Salomäki
Department of Child Psychiatry, University of Turku, Finland.
Venla
V
Lehti
Department of Child Psychiatry, University of Turku, Finland.
Dan
D
Sucksdorff
Department of Child Psychiatry, University of Turku, Finland; Nordic School of Public Health, Gothenburg, Sweden; National Institute for Health and Welfare, Finland.
Mika
M
Gissler
Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York, NY, USA; Department of Epidemiology, Columbia University, Mailman School of Public Health, New York, NY, USA.
Alan S
AS
Brown
D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000453:epidemiology*; D001724:Birth Weight; D016022:Case-Control Studies; D002585:Cesarean Section / Q000009:adverse effects* / Q000706:statistics & numerical data; D002648:Child; D002675:Child, Preschool; D005260:Female; D005387:Finland / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D016015:Logistic Models; D008297:Male; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D055815:Young Adult
Bipolar disorder; Fetal growth; Gestational age; Obstetric complications; Perinatal complications