Pre-morbid fertility in psychosis: findings from the AESOP first episode study

Individuals with psychotic illnesses are known to have a reduced fertility. It is unclear whether this is due to biological or social factors. Most fertility studies have been conducted in chronic schizophrenia, where confounders like medication and hospitalisation make this difficult to elicit. A less severe reduction of fertility has been observed in some ethnic minorities, but results are inconsistent. We sought to investigate pre-morbid fertility in an ethnically diverse sample of individuals with first-onset psychosis. Data were derived from 515 people with a first psychotic episode (FEP) and 383 controls. We made case-control comparisons of differences in the proportion of those with children (fertility rates) and mean number of children (MNC). Analyses were then stratified by diagnosis, gender and ethnicity, and adjusted for potential confounders. We found that FEP showed a reduced fertility rate (age-adjusted OR of having children 0.47 [95% CI=0.39, 0.56]), irrespective of diagnosis, and there was little evidence of confounding by gender, ethnicity, religious background, education level, or history of past relationships (fully adjusted OR=0.55, 95% CI=0.37, 0.80). Women had a somewhat greater reduction in fertility rates than men (Men: age-adjusted OR 0.61 [95% CI 0.42, 0.89]; Women: age-adjusted OR 0.46 [95% CI 0.31, 0.69]) and we could not find any evidence of ethnic differences in the degree of fertility reduction. FEP who had previously experienced a stable relationship had an MNC that was comparable to that of the general population and had a later onset of illness. This is the largest case-control study to date to investigate fertility in first-onset psychosis. Our data suggests that fertility is affected, even prior to the onset of a psychotic illness, and there are likely to be biological and environmental factors involved, but the former seem to have a stronger influence.