Fertility Rate Trends Among Adolescent Girls With Major Mental Illness: A Population-Based Study

Abstract

Fertility rates among adolescents have decreased substantially in recent years, yet fertility rates among adolescent girls with mental illness have not been studied. We examined temporal trends in fertility rates among adolescent girls with major mental illness. We conducted a repeated annual cross-sectional study of fertility rates among girls aged 15 to 19 years in Ontario, Canada (1999-2009). Girls with major mental illness were identified through administrative health data indicating the presence of a psychotic, bipolar, or major depressive disorder within 5 years preceding pregnancy (60,228 person-years). The remaining girls were classified into the comparison group (4,496,317 person-years). The age-specific fertility rate (number of live births per 1000 girls) was calculated annually and by using 3-year moving averages for both groups. The incidence of births to girls with major mental illness was 1 in 25. The age-specific fertility rate for girls with major mental illness was 44.9 per 1000 (95% confidence interval [CI]: 43.3-46.7) compared with 15.2 per 1000 (95% CI: 15.1-15.3) in unaffected girls (rate ratio: 2.95; 95% CI: 2.84-3.07). Over time, girls with major mental illness had a smaller reduction in fertility rate (relative rate: 0.86; 95% CI: 0.78-0.96) than did unaffected girls (relative rate: 0.78; 95% CI: 0.76-0.79). These results have key clinical and public policy implications. Our findings highlight the importance of considering major mental illness in the design and implementation of pregnancy prevention programs as well as in targeted antenatal and postnatal programs to ensure maternal and child well-being.