Birth Seasonality of Schizophrenia and Bipolar Disorder? A Review of Inpatient Records

Background: Numerous studies on seasonality of birth for mood disorders and schizophrenia have been published but findings are inconsistent 1. We aim to test the hypothesis of lack of seasonal birth differences in hospitalized Bipolar Disorder and Schizophrenia patients. Methods: 15969 inpatient records in UTHealth Harris County Psychiatric Center between 2012-2014 were enrolled (HSC-MS-14-0274). Patients birth months that were diagnosed as Schizophrenia (n=4178) and Bipolar Disorder (n=5303) according to the DSM IV Criteria were tabulated including admitting diagnosis. Texas Birth statistics between 1903-1997 were obtained as control group (n= 17096471). Results: There was no significant difference for winter births between schizophrenia patients and control group (P=0.738) and there was no significant difference for winter births between bipolar patients and control group either (P= 0.862). Mann Kendall Trend Analysis showed no significant trends of birth months for schizophrenia, bipolar and control groups. Limitations: The study limitations include being a retrospective study, inability to control for environmental factors, and recruiting from a single location. Conclusions: Our large sample showed no association between birth season or months with schizophrenia or bipolar disorder. Severe schizophrenia that requires admission may not be related with birth seasonality.

Automated summary

The study found no association between birth season or months with schizophrenia or bipolar disorder among hospitalized patients. Severe schizophrenia requiring admission may not be related to birth seasonality. Limitations include retrospective design, inability to control for environmental factors, and recruiting from a single location.