title: Obstetric conditions and risk of first admission with schizophrenia: a Danish national register based study.
abstract: A range of complications of pregnancy, abnormal fetal growth and development, and complications of delivery have been associated with increased risk of schizophrenia. Few studies have been able to adjust for a broad range of potential confounding factors. A national population nested case-control study based on Danish longitudinal registers was conducted to investigate the risk of schizophrenia associated with exposure to a range of obstetric events. The sample included 1039 first admissions to, or contacts with Danish psychiatric services with an ICD-8 or ICD-10 diagnosis of schizophrenia and 24, 826 individually matched controls. Adjusting for the other obstetric factors, family psychiatric history, and socio-economic and demographic factors, risk of schizophrenia was associated with maternal non-attendance at antenatal appointments (Incidence Rate Ratio (IRR) 2.08, 95% CI: 1.0, 4.4), gestational age of 37 weeks or below (IRR 1.51, 95% CI: 1.0, 2.2), maternal influenza (IRR 8.2, 95% CI: 1.4, 48.8), preeclampsia (IRR 2.72, 95% CI: 1.0, 7.3), threatened premature delivery (IRR 2.39, 95% CI: 1.4, 4.1), haemorrhage during delivery (IRR 2.43, 95% CI: 1.1, 5.6), manual extraction of the baby (IRR 2.15, 95% CI: 1.1, 4.4), and maternal sepsis of childbirth and the puerperium (IRR 2.91, 95% CI: 1.1, 7.9). There was no significant interaction between the obstetric factors and either sex or family psychiatric history. The data suggest a modest association between prematurity, indicators of hypoxia, maternal infections, and maternal behaviours and risk of the later development of schizophrenia after adjusting for a number of possible confounding factors.
authors.affiliation: National Centre for Register-based Research, Aarhus University, Taasingegade 1, Aarhus 8000 C, Denmark. mb@ncrr.dk
authors.forename: Majella
authors.initials: M
authors.lastname: Byrne
authors.forename: Esben
authors.initials: E
authors.lastname: Agerbo
authors.forename: Birgit
authors.initials: B
authors.lastname: Bennedsen
authors.forename: William W
authors.initials: WW
authors.lastname: Eaton
authors.forename: Preben Bo
authors.initials: PB
authors.lastname: Mortensen
mesh_terms: D000293:Adolescent; D000328:Adult; D001238:Asphyxia Neonatorum / Q000175:diagnosis / Q000453:epidemiology; D016022:Case-Control Studies; D003718:Denmark; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000175:diagnosis / Q000453:epidemiology; D008297:Male; D007744:Obstetric Labor Complications / Q000453:epidemiology*; D010343:Patient Admission / Q000706:statistics & numerical data*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011297:Prenatal Exposure Delayed Effects; D012042:Registries; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology* / Q000209:etiology / Q000235:genetics; D013223:Statistics as Topic