Objective: Previous research has suggested that patients with schizophrenia have fewer offspring compared to the general population. Reduced fertility in a disorder with a strong genetic component and an apparently stable incidence has implications for models of genetic transmission. There is also a need to obtain contemporary estimates of the prevalence of parenthood among subjects with psychotic disorders in order to inform service planning. The aim of this study was to determine the fertility and fecundity of a representative sample of individuals with psychoses who were in contact with mental health services, and to explore the interactions between age at first diagnosis and fertility.
Method: All clients of two community mental health clinics and an extended-care psychiatric hospital were surveyed. Data on diagnosis, age at first diagnosis, and the number and age of offspring were collected. Based on interviews with the proband and chart review, a genogram of the probands' family was drawn that identified sex, age, affected status and the number of offspring for each patient and their siblings.
Results: In total, 36% of all patients were parents. Most women with psychoses (59%) were mothers. Patients with psychoses had fewer offspring compared to their unaffected same-sex siblings. This was especially the case for men with non-affective psychoses. Higher levels of fertility were associated with a later age at first diagnosis.
Conclusion: The consistent finding of reduced 'reproductive fitness' in those with non-affective psychoses needs to be incorporated in the genetic epidemiology of these disorders. Despite this reduction in fertility and fecundity, many patients with psychoses are parents. Services need to remain mindful of the special needs of these patients.