In this umbrella review, we identified 11 factors: placenta abruption, placenta previa, celiac disease, mullerian anomaly, subclinical hyperthyroidism, subclinical hypothyroidism (SCH), thyroid peroxidase antibody, isolated hypothyroxinemia, depression during pregnancy, epilepsy in pregnancy, and maternal hepatitis C virus (HCV) infection (Table 1). The gene discussed is TPO; the disease is placenta praevia.