“…Among the 10 included studies, five adopted case-control designs (AbdelMalik et al, 2003; Deighton et al, 2016; Harrison et al, 2006; Helgeland & Torgersen, 2005; Wilcox & Nasrallah, 1987) and five adopted cohort designs (Ledoux et al, 2022; Lopez et al, 2022; Massagli et al, 2004; Orlovska et al, 2014; Timonen et al, 2002). Four studies were carried out in the United States (Deighton et al, 2016; Lopez et al, 2022; Massagli et al, 2004; Wilcox & Nasrallah, 1987), whilst the remaining six studies were undertaken in other places including Canada (AbdelMalik et al, 2003; Ledoux et al, 2022), Denmark (Orlovska et al, 2014), Finland (Timonen et al, 2002), Norway (Helgeland & Torgersen, 2005), and Sweden (Harrison et al, 2006). Five studies measured schizophrenia as an outcome (AbdelMalik et al, 2003; Harrison et al, 2006; Helgeland & Torgersen, 2005; Timonen et al, 2002; Wilcox & Nasrallah, 1987), four studies measured psychosis (Harrison et al, 2006; Ledoux et al, 2022; Massagli et al, 2004; Orlovska et al, 2014), and two studies investigated sub-threshold symptoms of psychosis (Deighton et al, 2016; Lopez et al, 2022).…”