AFP and preeclampsia: Previous studies have shown that D-dimer levels might predict a higher risk of pregnancy failure in women who underwent in-vitro fertilization and guide anticoagulant treatment in recurrent pregnancy loss associated with antiphospholipid syndrome; the high levels of D-dimer detected at more than 20 weeks of gestation were related to the severity of preeclampsia and maternal serum D-dimer combined with alpha-fetoprotein (AFP) and free β-subunit of human chorionic gonadotropin (free β-hCG) at the second trimester of pregnancy might be used to predict hypertensive disorders of pregnancy (12–15).