Gestational maternal C-­reactive protein and risk of bipolar disorder among young individuals in a Nationwide Birth Cohort

•Inflammation in pregnancy is associated with increased risk of psychiatric disorders.•CRP is marker of inflammation from both infectious and noninfectious exposures.•Elevated maternal CRP is associated with an increased risk of schizophrenia and ASD.•No significant associations were seen with elevated maternal CRP and offspring BPD.•Maternal inflammation may be a factor that differentiates schizophrenia from BPD.

ObjectivesC-reactive protein (CRP) is a well-established general marker of inflammation from both infectious and noninfectious exposures. Previous studies have shown that maternal CRP is associated with an increased risk of autism and schizophrenia. The aim of this study was to examine the association between early to mid-gestational serum CRP levels, prospectively assayed in maternal sera, and the risk of bipolar disorder (BPD).MethodsThis study is derived from the Finnish Prenatal Study of Bipolar Disorder (FIPS-B), based on a nested case-control study design. A total of 378 BPD cases and 378 controls, matched on date of birth and sex, with available maternal sera were identified from Finnish nationwide registers. Maternal CRP levels were assessed using a latex immunoassay from archived maternal serum specimens, collected primarily during the first and second trimesters of pregnancy.ResultsIncreasing maternal CRP, examined as a continuous variable, was not associated with BPD (OR=0.92, 95% CI: 0.81-1.05, p=0.24). The result did not change appreciably following adjustment for potential confounders. There were no associations between CRP in the highest quintile or decile, compared with their respective reference groups, and BPD.LimitationsThe limitations of the study include: relative young age of the cohort and availability only of a single marker of inflammation.ConclusionsIn contrast to previous findings on schizophrenia and autism, gestational maternal serum CRP levels were not associated with an increased risk of BPD. It is likely that maternal inflammation may be an additional factor that differentiates schizophrenia from BPD.