Birth seasonality and height in patients with schizophrenia: a multi-institutional cohort study.

PURPOSE: Schizophrenia is a psychiatric condition characterized by different physical liabilities, including reduced height, increased medical comorbidity, and reduced life expectancy. Schizophrenia stems from gene-environment interactions, with winter birth being a widely replicated environmental risk factor associated with more severe outcomes. We aim to investigate the association between winter birth and height in individuals with schizophrenia. METHODS: 15181 individuals diagnosed with schizophrenia and with recorded height and date of birth, comprising 7414 males and 7767 females from the Chang Gung Research Database from Taiwan, were included. RESULTS: Winter-born patients were the shortest (161.9 ± 8.8 cm), but the seasonal effect was non-significant after adjusting for sex and age (F = 2.4, p = 0.063). February-born patients were the shortest (161.5 ± 8.8 cm), and the monthly effect was significant after adjusting for sex and age (total sample, p = 0.038; females, p = 0.021). No significant effect was detected in male patients regarding the season/month of birth. After correction for multiple comparisons, the seasonal contrasts were no longer significant, whereas a subset of month-of-birth contrasts persisted. CONCLUSIONS: Our results revealed a descriptive gradient where winter birth (specifically February) was associated with the shortest adult stature, a trend more pronounced among female patients. These findings suggest that winter birth is not only a risk factor for schizophrenia but may also impact anthropometry. Further research needs to examine potential etiologic causes for this association.